An unidentified assailant threw a fragmentation grenade early Monday at the residence of Francisco Ayon, the mayor of the western Mexican city of Guadalajara, wounding a police officer, police spokesmen said.

The mayor was not at home when the attack was staged on his residence near downtown Guadalajara, the capital of the western state of Jalisco, police said.

The grenade exploded on a patrol car parked outside the house, slightly wounding one of the two officers inside.

The assailant rode up to the house on a motorcycle, threw the grenade and sped away, investigators said.

Police searched for the assailant, but no arrests have been made and the motive for the attack has not been determined.

The blast damaged the patrol car and a nearby business, police said.

Ayon became mayor in January, when Aristoteles Sandoval resigned to run for governor of Jalisco on the Institutional Revolutionary Party, or PRI, ticket. Sandoval won the governorship in the July 1 general elections.

The mayor is going about his activities normally on Monday, city officials said.

Guadalajara, a city of 1.5 million people, has been affected by a turf war between rival drug gangs.

The Jalisco Nueva Generacion cartel has been battling Los Zetas, considered Mexico's most violent drug cartel, for control of smuggling routes.

The Jalisco Nueva Generacion organization was created following the death of Ignacio "Nacho" Coronel, a top Sinaloa drug cartel boss, in 2010.

Erick Valencia Salazar, considered the successor to Coronel, was arrested on March 9 in Zapopan, a city in Jalisco.

Valencia was responsible for expanding the reach of the Jalisco Nueva Generacion cartel, officials said.

He was the operations chief for the Jalisco Nueva Generacion cartel before Coronel's death in a shootout with soldiers in July 2010.

The cartel split into two criminal organizations after Coronel's death, with Nemesio Oseguera Cervantes taking over the leadership of Jalisco Nueva Generacion with Valencia's backing, while Elpidio Mojarro Ramirez formed the La Resistencia gang. EFE