The Mariposa Port of Entry was closed at about 7:50 p.m. for nearly 35 minutes Monday after officers reported shots fired toward the passenger-vehicle inspection area.

“We closed the port to keep travelers and our officers safe and routed traffic” to the Dennis DeConcini Port of Entry, said Chief Brian Levin of Customs and Border Protection.

Details were “sketchy” Monday night, but in an interview, Levin said the shots were fired from Mexico.

“Procedurally, one of the first things we do is alert Mexican officials, usually C-4, and it is broadcast (to other agencies) from there,” Levin said. The C-4 is the equivalent of the 911 Emergency System in the United States..

Cesar Barron, of Radio XENY in Nogales Sonora reported army troops and law enforcement personnel responded to the scene on the Mexican side of the border.

By 8:25 p.m., Levin said it was determined that the danger had passed and the port was reopened.

“We don’t stay closed any longer than we have to,” he said, adding that extra personnel were called into duty and that all were on heightened alert.

It was another in a string of violence including the murders of at least 15 men during the past week.

On Sunday, authorities discovered the six decomposing bodies partially buried in a vacant lot about two miles south of the border on Boulevard del Ensueno. Investigators believe they had been dead for at least five days.

Another two men were killed Saturday night following a gun battle that also left three injured.

On Friday, Sonora Gov. Guillermo Padres Elias came to the border unannounced for private meetings with other state, federal and local officials to develop strategies against the murders and violence that has plagued the city in the past two weeks. No details of the two-hour meeting were revealed publicly.

That evening another man was killed and decapitated. His body was found in the parking lot of the Nuevo Dia newspaper about 2.5 miles south of the Mariposa port on Luis Donaldo Colosio Boulevard.