Police in El Salvador say gunmen boarded a bus in a town near the capital and opened fired on passengers, killing six.

National police director Rigoberto Pleites said another five people were wounded during the Friday bus attack in the town of San Luis Talpa near San Salvador.

Pleites said witnesses told police the assailants were gang members dressed in uniforms similar to those issued to road maintenance workers.

He said investigators haven’t confirmed they belonged to a gang.

Police Commissioner Mauricio Ramirez said there have been threats of increased violence in the country in the coming days, but he didn’t provide any other details.