SAN SALVADOR (Reuters) – El Salvador’s police arrested seven suspected gang members yesterday accused of setting a city bus on fire and killing 14 people, one of the worst attacks on civilians by violent street gangs.

The attackers brandished guns to stop the bus late on Sunday as it passed through a dangerous neighborhood in the outskirts of the capital city of San Salvador. They shot at the bus, doused it with gasoline and lit it on fire as passengers scrambled to escape, authorities said. “We’re talking about 14 people who were burned to death because they could not leave the bus, according to the reports that I have had,” President Mauricio Funes said in a statement.

“(This is an act of) terrorism and I call it that because there is no doubt that the attackers were trying to sow terror in the population.”

Authorities said they were still investigating the motive for Sunday’s killings.

Youth gangs, which largely started in the United States and expanded in El Salvador when criminal immigrants were deported back home, run large extortion rings in the country, demanding payments from bus drivers and store owners under the threat of death. Branches of the same gangs can be found across Central America.