SAN DIEGO

Authorities arrested 96 people, most of them students, as part of an undercover drug investigation at San Diego State University that began after a student’s fatal cocaine overdose last spring, authorities said Tuesday.

Authorities seized several guns, at least $60,000 in cash, marijuana, psychedelic mushrooms, hash oil, methamphetamine and illicit prescription drugs, authorities said. Two kilograms of cocaine and 350 ecstasy pills also were seized, officials said.

Eighteen students were arrested Tuesday when nine search warrants were executed at various locations, said Jesse Rodriguez, San Diego County assistant district attorney.

About 75 students faced charges. Those arrested included a student who was about to receive a criminal justice degree and another who was to receive a master's degree in homeland security. Some defendants were scheduled to appear in state court to face charges Tuesday.

During the probe, dubbed Operation Sudden Fall, more than 130 undercover drug buys were made at locations including fraternity houses, student parking areas and in student dormitories, authorities said.

A member of the Theta Chi fraternity sent out a mass text message to his “faithful customers” stating that he and his “associates” would be unable to sell cocaine while they were in Las Vegas over one weekend, according to the DEA.

Shawn Collinsworth, executive director of the national office of the college social organization, said he was told by two of the SDSU fraternity chapter's leaders that four of its members were arrested. He added the fraternity is cooperating with the investigation.

“It isn’t behavior becoming of Phi Kappa Psi,” Collinsworth said.

University police and federal drug agents worked together in the investigation, which was inspired when a student overdosed on cocaine in May 2007.