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Families crossing the Venezuelan border with Colombia early Thursday morning.Credit Meridith Kohut for The New York Times

SAN ANTONIO DEL TÁCHIRA, Venezuela — At night and in the early morning, they wade across the thigh-deep river in Colombia, with televisions, refrigerators and other household possessions on their backs. By day, watched by gun-toting soldiers, they line up to cross what was once a busy international bridge now under military lockdown, dragging roller suitcases while their children shoulder school backpacks.

Hundreds of Colombians are fleeing across the border, running from a crackdown on immigrants initiated by Venezuela’s president, Nicolás Maduro.

“It’s heartbreaking,” said Handerles Suárez, 25, a construction worker, as he waited with his wife and baby daughter at dusk to cross the Simón Bólivar Bridge to his native Colombia. He said he had lived in Venezuela for 10 years, but now, seeing his countrymen rounded up and deported, their houses marked for demolition by the government, he decided to leave voluntarily rather than risk the uncertainty of a forced departure.

“Venezuela has given us everything,” he said, tears in his eyes. “It’s been like a second mother to us.”

Last Friday, Mr. Maduro ordered troops to close the border here, shutting bridges to almost all traffic and commerce with Colombia. And he declared a state of emergency in a stretch of territory along the border, allowing warrantless searches and placing restrictions on public gatherings or protests.

At the same time, soldiers in this Venezuelan border town began house-to-house searches in a sprawling slum, checking identity papers and rounding up hundreds of Colombian citizens, many of whom had lived in Venezuela for years. They were made to sit in a dusty soccer field under the baking sun for hours before being sent to the bridge and kicked out of the country.

Officials said that more than 1,000 people were deported.

In closing the border, Mr. Maduro said he was responding to an episode in which three Venezuelan soldiers were shot and wounded. The details remain hazy, but Mr. Maduro said it was an attack by a Colombian paramilitary group obeying the orders of a former Colombian president, Álvaro Uribe, whom he has frequently described as an enemy bent on overthrowing his leftist government.

Mr. Maduro said the border shutdown would last indefinitely, and that he planned to expand the state of emergency to other parts of the country.

But to analysts and those caught in the crackdown, the state of emergency was inextricably tied to the economic and political crisis gripping Venezuela, with politicians looking for someone to blame.

Mr. Maduro says the Colombian immigrants include smugglers who spirit much-needed goods out of his country, worsening chronic shortages; black marketeers who drive up prices for products in Venezuela, where inflation is soaring; and right-wing paramilitary groups that Mr. Maduro accuses of seeking to attack his government, under orders of his enemies at home and abroad.

For now, the focus of Mr. Maduro and the hundreds of soldiers he dispatched has been on a large slum that hugs the Táchira River separating the two countries, an area he says is a nest of paramilitary groups, brothels, criminals and smugglers.

During a televised news conference this week, he vowed to raze the slum.

“We’re going to knock down all the houses there, just so you know,” Mr. Maduro said. “Not a single house will remain.”

The warnings set off despair and anger here in the neighborhood, where a backhoe has already started knocking down houses. Many people said they were hard-working Venezuelan citizens or Colombians with legal residency, and they asked why their homes were slated to be torn down.

“I don’t see the justification at all,” said Jairo Gómez, 55, a Venezuelan who has a small business selling empanadas. He built a house here 13 years ago and now fears he will lose it.

In an area of the slum, named after the Argentine revolutionary hero Che Guevara, a backhoe was brought in this week and began knocking down the cinder block houses.

On Wednesday night, some families were busy dismantling their own homes to salvage the construction materials so they could be sold or used again later.

“You just want to lie down and never wake up,” said Tatiana Cerna, 33, a Colombian who said she lived here legally with her Venezuelan husband and child. A few yards from other houses that had already been demolished, the family was working with hand tools under the moonlight to take apart their home, brick by brick, beam by beam.

“This is the kind of family that lives here,” said Ms. Cerna, a seamstress whose husband is a taxi driver. “If they want to stop the smuggling, I think the national guard itself is involved. To come and knock all this down is not the solution.”

Mr. Maduro’s popularity is extremely low because of the country’s economic struggles, and the country is approaching a crucial legislative election in December that could enable the opposition to win a majority for the first time in years.

While closing the border and evicting immigrants may stir some nationalist sentiment, it could backfire in a country where many naturalized Venezuelans vote and many other voters have Colombian relatives.

“We were Chavistas, but never again,” said Wilson Velazco, 32, Ms. Cerna’s brother-in-law, covered in dust from the demolition and using the Spanish term for the followers of Mr. Maduro’s predecessor, Hugo Chávez.

“Maduro is a clown, not to use a more offensive word,” he said. “If Chávez were alive, he never would have permitted this.”

The actions here have also brought strong condemnation from Colombian officials. On Tuesday, President Juan Manuel Santos of Colombia condemned what he called the mistreatment of deported Colombians.

“Raiding houses, removing the inhabitants by force, separating families, not allowing them to take with them their few belongings and marking the houses in order to demolish them later on, these are totally unacceptable actions that recall bitter episodes of humanity that must not be repeated,” Mr. Santos said.

Each country has long pointed to the other in times of internal tension. Relations reached a low point when the conservative Mr. Uribe and the leftist Mr. Chávez were presidents and engaged in a heated ideological struggle.

Mr. Uribe accused Mr. Chávez of supporting guerrilla groups fighting the Colombian government. Tensions cooled after Mr. Santos became president in 2010 and Venezuela helped broker peace talks between Colombia and its largest rebel group.

But this week the acrimony returned, and on Thursday both countries announced that they had recalled their ambassadors.

“Venezuela’s problems are made in Venezuela, not in Colombia,” Mr. Santos said. Mr. Maduro, in turn, called Mr. Santos a liar and accused him of neglect. “Colombia has turned into a net exporter of poor people, fleeing misery, fleeing war,” Mr. Maduro said on Thursday. 

Mr. Maduro defended his border policy. “I’m not anti-Colombian,” he said this week, adding that 5.6 million Colombians live in Venezuela, which has a total population of about 30 million. “We love the Colombian people.”

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