Investigators are looking at whether the two professors wounded by a parcel bomb at a university in the central state of Mexico, which surrounds the Federal District and forms part of the Mexico City metropolitan area, were targeted for personal or professional reasons, officials said Tuesday.

The homemade bomb exploded Monday in a faculty office at a Monterrey Institute of Technology campus in Mexico state and was in a package addressed to professor Armando Herrera Corral, Mexico state Attorney General Alfredo Castillo told MVS Radio.

A gardener found the package on campus and gave it to a security guard, Mexican media reported.

Herrera Corral, an information technology expert, took the package to professor Alejandro Aceves Lopez's office to show him what appeared to be an award.

The bomb exploded in the office, wounding the two professors.

The package bore a message saying that anyone other than the addressee who opened the parcel would be prosecuted, Castillo said.

The message on the package shows the bombers "wanted to make sure it was this teacher (Herrera) specifically who opened it," the AG said.

Herrera sustained just a few shrapnel wounds in the foot, while Aceves's condition is "a little bit more complicated," but he is out of danger, Castillo said.

Investigators are working on the theory that the attack may have been motivated by a "personal issue against the teacher" or because some person or group is "angry about the development of information technologies," Castillo said.

Authorities have identified groups in the past that oppose the spread of technology, the AG said, without identifying the groups.

Investigators are looking at two similar cases in which bombs were found but failed to go off, Castillo said.

Small bombs have been detonated at bank ATMs in Mexico City over the past few years, with anarchist groups blamed for the attacks.

The AG's office will also look at whether "the construction of the bomb" that exploded at the university is similar to that of bombs used in other attacks, Castillo said.

The package contained a message that partially burned in the explosion, but something about "hurting or killing teachers and students," can be discerned, the AG said.

Monterrey Tech, Mexico's most prestigious private university, has 27 campuses across the country and operates five preparatory schools.

The institution's main campus in the northern industrial metropolis of Monterrey was the scene in March 2010 of a pitched battle between army troops and gunmen working for a drug cartel.

Two graduate students were killed by soldiers who mistook them for the men they were pursuing.