SAN SALVADOR, El Salvador (AP) _ Imprisoned gang members enraged by a tough new anti-crime law rioted and seized about 100 hostages at two Salvadoran prisons Thursday.

Inmates' friends and family members were visiting prisons in the cities of Cojutepeque and Chalatenango when members of the M-18 street gang blocked entrances, Rodolfo Garay, director of the national correctional system, told reporters. The hostages also included prison staff members.

Garay said the inmates were not armed but refused to let anyone enter or leave either prison. Police and prison guards encircled the facilities, but did not move in for fear of triggering further violence. Garay said federal authorities had begun negotiating with gang leaders.

At Cojutepeque, 20 miles east of San Salvador, an estimated 60 women, six men and three children were being held. At Chalatenango, 95 miles north of the capital, the hostages included 40 people identified as mostly women visitors.

Garay said the rebellions were in response to a zero-tolerance law that took effect Aug. 30 that makes it illegal to be a member of a street gang. Modeled after a similar measure in neighboring Honduras, the law largely allows police to sweep the streets, imprisoning all suspected gang members.

``Their demands are strictly political,'' Garay said, referring to the new law.

Garay said the uprising's organizers said the standoff would continue until they were allowed to negotiate directly with the federal human rights ombudsman and Salvadoran Roman Catholic Archbishop Fernando Saenz Lacalle.

He said officials expected the prisoners to continue holding the hostages all night Thursday. He said many of those being held were hostage-takers' family members who had little fear of being harmed.