MEXICO CITY – Mexico's government offered a reward of nearly US$100,000 Wednesday for information leading to the capture of gunmen who killed an 11-year-old girl and seven others in a northern city.

The eight were leaving a party Sunday when gunmen sprayed their cars with bullets in Guamuchil in Sinaloa state. Also among the victims were two 17-year-old boys and two women aged 18 and 19.

The attack was shocking even for Sinaloa, home base of a powerful drug cartel of the same name and one of the states worst hit by a wave of drug-related violence sweeping over Mexico.

The Public Safety Department said 1 million pesos (US$97,000) would be awarded to anyone with information leading to the arrest of the gunmen.

Authorities have not named any suspects or possible motives in the shooting, but a Public Safety Department official said the reward was offered because the victims appeared to be innocent. The official spoke on condition of anonymity because he was not authorized to speak to the media.

Two days after the shooting, the government sent 1,260 more federal police to Sinaloa, bringing the total number to 2,000.

Despite the reinforcements, a Sinaloa state police commander, Salomon Diaz, was gunned down Wednesday in Culiacan, the state capital, according to the Sinaloa Attorney General's office.

Drug gangs have stepped up attacks against police and government officials since President Felipe Calderón deployed more than 25,000 troops the country to root out traffickers. More than 450 police, soldiers, prosecutors or investigators have been killed since Calderón took office in 2006.

In Ciudad Juarez, a border city across from Texas, more than 100 traffic police protested outside the mayor's office Wednesday after a shooting killed one of their colleagues and left another brain dead.

Eds: Associated Press Writer Marina Montemayor contributed to this story from Ciudad Juarez, Mexico.