An unprecedented surge of 4,000 migrants streamed across the US border with Mexico in to Eagle Pass, Texas, on Wednesday — forcing the overwhelmed city to declare an emergency.

Border patrol sources said they join approximately 7,500 other migrants who have handed themselves in over the last week.

The surge is the largest since 15,000 Haitian immigrants camped out under the bridge in neighboring Del Rio, Texas, in September 2021, officials said. That incident resulted in a major humanitarian crisis.

City Mayor Rolando Salinas said the mob, many of them from Venezuela, has overrun the Mission Border Hope shelter in the city, where asylum seekers are processed.

“One of the situations is that a lot of these [migrants], they’re single males and they don’t want to listen to instructions and they’re leaving the facility,” the mayor said.

“Not all of these people come in peace.”

He also said the huge influx over the last week — close to 50% of the city’s 29,000 population — has “taken a toll on our local resources, especially our local police force and our fire department.”

Processing migrants usually takes around two days, but with the huge influx could take a lot longer, border sources told The Post. During that time all the migrants have to be held in custody, which also provides a challenge for authorities.

Among those now detained at Eagle Pass is Roberto Emilio Vasquez-Santamaria, a 64-year-old Peruvian immigrant who is charged with murder in the slaying of another man in the Texas city, Fox News reported.

Vasquez-Santamaria illegally crossed into Texas in May, but was released because he officials did not identify a criminal record for him. Immigration and Customs Enforcement ordered him to return to court in 2025, the outlet reported.

After he was released into the community he killed a person, although details of the murder have not been released by the local sheriff.

“It’s obviously a security issue,” said US Rep. Eddie Morales, a Democrat whose district includes Eagle Pass.

“I am aware that there are 2,000-4,000 under the [International] Bridge right now and more are coming. We’ve also been in contact with Union Pacific [railroad, which runs across the bridge] to make sure they are adequately providing security so that they are not crossing on the railroad tracks.

“All this to say is that there is a concerted effort to try to get a handle on this situation,” he said.

The Texas crisis is just the latest where unvetted migrants have pushed their way into the country. Last month thousands crossed the border via 114floodgates in Arizona that were welded open by federal officials to accommodate the migratory patterns of an endangered species of antelope and potential floodwaters.

Salinas said Wednesday that the new emergency declaration will allow Eagle Pass to apply for federal and state aid to help deal with the sudden influx of undocumented migrants.

“This is just a measure that we have to take to make sure we maintain order here in the city of Eagle Pass,” he said. “We’re going to use that money to reimburse fire, reimburse police and any other expenses that the city has to make.

“We do have reports that there are other caravans coming to Eagle Pass, so we want to be prepared for any scenario,” he added.