A car bomb killed at least two police officers and injured another seven outside the home of a top security official in Mexico's northeast state of Tamaulipas, state officials said Tuesday.

Both victims were bodyguards assigned to protect Public Security Secretary Rafael Lomeli Martinez, according to state government secretary Morelos Canseco.

Officials said an initial explosion shortly before midnight Monday drew federal and state police to the scene and minutes later a car bomb went off, killing the two officers and injuring others in the capital Ciudad Victoria's residential district of Campestre.

Lomeli was not at home at the time of the explosion, one day after general elections in Mexico.

Officials believe the explosions are the work of organized crime groups in retaliation for increased anti-crime measures put in place by the state government, especially in the run-up to elections.

Last Friday, an explosion went off in the parking lot of the mayor's office in Nuevo Laredo, Tamaulipas, injuring four people. On March 19, a car bomb exploded outside the offices of the Ciudad Victoria daily Expresso. Luckily no one was injured, local media reported.

Tamaulipas is one of the states in Mexico which are plagued by drug-related crimes, with the Zetas and Gulf cartels battling each other for the control of drug shipping routes to the United States.