There have been nearly 100 murders in Tijuana this month alone
A teenage girl was among 11 people shot dead in suspected drug-related violence at the weekend in the northern city of Tijuana, authorities in Mexico say.
In one attack, masked gunmen opened fire in a pool hall, killing five people, while the girl, 14, and two men were killed in a shootout in a street.
The murders happened just hours after at least 1,000 people marched through Tijuana to demand an end to violence.
The city, on the US-Mexico border, has seen more than 600 murders this year.
Across Mexico, more than 4,000 people have died in drug-related violence in 2008, as gangs fight each other and the security forces.
Correspondents say the surge in violence is related in part to the successes the Mexican authorities have had in recent months in arresting key members of the powerful drug cartels.
'God save us'
The latest killings in Tijuana, which took place within 24 hours, continued a grisly trend in violence, with the city seeing nearly 100 murders this month alone.
The girl and two men were shot in a street just before midnight on Saturday, state prosecutors said.
Also late on Saturday, attackers using assault rifles burst into the pool hall, killing four men and a woman and injuring five others.
Three further murders were reported early on Sunday.
Tijuana residents had marched through the centre of the city on Saturday, carrying placards reading "God save us" and calling for greater efforts to combat violent crime.