MIAMI — Miami police on Sunday searched for a motive for a shooting rampage in which six people were killed by a gunman who set his apartment on fire before shooting several neighbors and taking others hostage.

They said they were investigating reports that the man, Pedro Alberto Vargas, 42, was in the process of being evicted and had had disputes with the building’s management.

More than 100 police, including SWAT teams, stormed an apartment in Hialeah, a heavily-Hispanic suburb of Miami, in a pre-dawn raid on Saturday, killing Vargas and rescuing two hostages.

“When we found him he still had plenty of live rounds of ammunition,” Hialeah Police spokesman Carl Zogby told reporters. “This was an irrational act and many times there is no rational explanation.”

The weapon used in the incident, a 9-millimeter Glock handgun, was purchased legally in 2010, Zogby said.

Vargas, who arrived in the United States from Cuba in 1997, was described as a part-time graphic artist who kept largely to himself and cared for his elderly mother. He became a U.S. citizen in 2004, according to El Nuevo Herald, south Florida’s main Spanish-language newspaper.

He graduated from Miami Dade College with a degree in graphic design. There were no pending civil or criminal cases filed against him in Miami-Dade County courts.

Among the victims were two building managers and several neighbors, including a 17-year-old girl who police say was shot while trying to hide in a bathtub.

Vargas also fired 10 to 20 shots into the street, killing a man who was walking home with his 9-year-old son whom he had just picked up from boxing practice, police said.

It was the worst Miami area shooting since 1982, when 51-year-old Carl Robert Brown killed nine and wounded three others with a pump-action shotgun after a dispute over a $20 lawnmower repair.

Vargas held a permit to carry a concealed weapon. Police gave no information on where he bought the gun or details from the two-page questionnaire on the permit’s application. He had no military background and there were no reports of any psychiatric issues.

According to El Nuevo Herald neighbors knew little of the man other than that he exercised often and was regularly seen wearing gym shorts and running shoes. Neighbors say he regularly took his 83-year-old mother to doctor’s appointments.

The shooting started after Vargas set fire to his apartment as well as a large amount of cash. Vargas’ mother told police it was $10,000 drawn from his savings account, though the amount remains unconfirmed.

“Much if not all was burned,” Zogby said.