MEXICO CITY – Five state police officers were killed in the western Mexican state of Jalisco by grenade-lobbing gunmen who fired more than 800 bullets in the attack, authorities said Thursday.

The officers came under fire Wednesday night as they prepared to search a car they had just stopped in the town of Lagos de Moreno outside the western city of Guadalajara, the Jalisco state public safety department said in a statement.

An unknown number of assailants arrived in two pickup trucks. Two bystanders also were wounded, the department said.

State Public Safety Secretary Luis Carlos Najera said authorities suspected the Zetas, an infamous group of hit men tied to the Gulf cartel. The Zetas have a history of aggression against Jalisco police, Najera told the Megaradio station.

The federal Attorney General's Office announced a reward of 5 million pesos (US$407,000) for information leading to the capture of those behind the attack.

Meanwhile in Ciudad Juarez, across the U.S. border from El Paso, Texas, two state police officers were shot to death by gunmen in another car as they drove along a busy avenue, said Alejandro Pariente, a spokesman for the Chihuahua state prosecutor.

Hours after the Wednesday killings, a funeral wreath was left outside the state police headquarters in Ciudad Juarez, Pariente said. The wreath was accompanied by a threatening message and the name of the two slain officers and other policemen.

No suspects were named in the shooting.

Police increasingly have come under attack from drug cartels fighting a nationwide crackdown. In Ciudad Juarez, several officers have been gunned down after their names appeared on hit lists left in public.

Across Mexico this year, more than 3,000 people have been killed in violence blamed on the drug trade.

Also on Thursday, the Attorney General's Office announced the arrest of seven members of a third-division football team, the Mapaches de Nueva Italia, in a drug investigation. One of the seven was a suspected member of a drug gang known as La Familia, which operates in the western state of Michoacan.

No charges have been filed against the seven, and officials did not give any other details on the investigation.

The seven were arrested Wednesday in the training center for the Aguilas de la America, one of Mexico's most popular football teams.

The Mexico Football Federation said it would expel the Mapaches if the team was found to be involved in any illegal activities, or if any of its directors were charged with a crime.

Associated Press Writer Carlos Rodriguez contributed to this report.