MEXICO CITY - At least 17 suspected cartel gunmen and four police were killed during shootouts over the weekend in a Mexican town near the U.S. border, days after U.S. President Donald Trump raised bilateral tensions by saying he would designate the gangs as terrorists.

The government of the northern state of Coahuila said state police clashed at midday Saturday with a group of heavily armed gunmen riding in pickup trucks in the small town of Villa Union, about 40 miles southwest of the border city of Piedras Negras.

Standing outside the Villa Union mayor's bullet-ridden offices, Coahuila Governor Miguel Angel Riquelme told reporters the state had acted "decisively" to tackle the cartel henchmen. Four police were killed and six were injured, he said.

The City Hall of Villa Union is riddled with bullet holes after a gun battle between Mexican security forces and suspected cartel gunmen, Saturday, Nov. 30, 2019. Gerardo Sanchez / AP

The fighting went on for more than an hour, during which ten gunmen were killed, three of them by security forces in pursuit of the gang members, Riquelme said Saturday.

Authorities announced another seven suspected cartel gunmen were killed in an early Sunday morning shootout, bringing the number of dead to at least 21.

At about noon on Saturday, heavy gunfire began ringing out in Villa Union, and a convoy of armed pickup trucks could be seen moving around the town, according to video clips posted by social media users. Others showed plumes of smoke rising from the town.

Reuters could not vouch for the authenticity of the images.

An unspecified number of people were also missing, including some who were at the mayor's office, the governor said.

Riquelme said authorities had identified 14 vehicles involved in the attack and seized more than a dozen guns. The governor said he believed the gunmen were members of the Cartel of the Northeast, which is from Tamaulipas state to the east.

A wall of the room of a home is riddled with bullet holes after a gun battle between Mexican security forces and suspected cartel gunmen, in Villa Union, Mexico, Saturday, Nov. 30, 2019. Gerardo Sanchez / AP

The outbreak of violence occurred during a testing week for President Andres Manuel Lopez Obrador, who on Friday said he would not accept any foreign intervention in Mexico to deal with violent criminal gangs after Trump's comments.

Lopez Obrador said Mexico would handle the problem, a view echoed by Riquelme as he spoke to reporters.

"I don't think that Mexico needs intervention. I think Mexico needs collaboration and cooperation," said Riquelme, whose party is in opposition to Lopez Obrador. "We're convinced that the state has the power to overcome the criminals."

In an interview aired on Tuesday, Trump said he planned to designate the cartels as terrorist organizations, sparking concerns the move could serve as a prelude to the United States trying to intervene unilaterally in Mexico.

U.S. Attorney General William Barr is due to visit Mexico next week to discuss cooperation over security.

Lopez Obrador took office a year ago pledging to pacify the country after more than a decade of gang-fueled violence.

A series of recent security lapses has raised questions about the left-leaning administration's strategy.

Criticism has focused on the Nov. 4 massacre of nine women and children of U.S.-Mexican origin from Mormon communities in northern Mexico, and the armed forces' release of a captured son of drug lord Joaquin "El Chapo" Guzman under pressure from cartel gunmen in the city of Culiacan.

Coahuila has a history of gang violence, although the homicide total in the state that borders Texas is well below where it was seven years ago. National homicide figures are pushing record levels.