BOGOTA, Colombia (AP) _ At least 10 inmates died in a violent shootout between prisoners in Bogota on Thursday, officials said.

Guards were attempting to restore order at the La Picota federal penitentiary, prisons spokesman Rocio Devia said.

The bloody outbreak appeared to be a turf war between prisoners in two wards housing a mix of leftist guerrillas, common criminals and drug traffickers, Devia added.

Gang fights are common in the South American country's filthy and overcrowded prisons. Guns and knives are easily smuggled past corrupt guards.

More than 300 prisoners have been killed and about 900 have escaped from Colombian prisons since 1997, according to official statistics.

Also Thursday, an explosion in a neighborhood grocery store in the western city of Cali killed four people and seriously injured six others.

Police had ventured no theory as to who planted the explosive or why.