WASHINGTON (CNN) -- About 100 people, including students majoring in homeland security and criminal justice, were arrested Tuesday in an undercover drug sting at San Diego State University, officials said.

Officials say the evidence seized includes 50 pounds of marijuana, four pounds of cocaine and 350 ecstasy pills.

Among those arrested, 75 were students, one of them a criminal justice major charged with possession of guns and cocaine, authorities said. One student allegedly dealing cocaine was a month short of obtaining a master's degree in homeland security at the California school and worked under campus police as a student community service officer.

Campus police initiated the investigation about a year ago, after a student's fatal overdose in May 2007, university President Steve Weber said. About five months ago, as the investigation evolved, campus police sought and received help from the U.S. Drug Enforcement Administration.

There was a second overdose death in February at a fraternity house.

"If proven guilty, these individuals have preyed on students and have ruined hundreds of lives," Weber said. In addition to facing criminal charges, the students have been suspended from school and evicted from campus housing, he said.

Twenty-one people who are not students were arrested recently on a variety of drug charges, officials said.

Damon Mosler, chief of the narcotics division for the San Diego County District Attorney's Office, was surprised by what he described as the dealers' openness about what they were doing.

"They weren't picky about who they sold to," he said, alleging that undercover officers would simply call them and say, " 'Hey, I heard you deal. Will you sell to me?'

"And they did."

Officials say the evidence seized as part of Operation Sudden Fall includes four pounds of cocaine, 50 pounds of marijuana and 350 ecstasy pills. Authorities also took one shotgun, three semiautomatic pistols and $60,000.

In all, authorities confiscated more than $100,000 worth of drugs, Mosler said. Bags of marijuana weighing four or five pounds would sell for $4,000 to $5,000, he said, and a kilogram of cocaine would sell for about $17,000.

Before going to Las Vegas for the weekend, fraternity members involved in the sale of drugs sent text messages to their customers saying, "We're going to close out our inventory" and inviting them to "buy the cocaine at discounted prices," Mosler said.

After the weekend, they sent another text message saying they were back and ready to do business, Mosler said.

Search warrants were carried out last week on suspects' houses off campus, and search warrants were served Tuesday at on-campus housing.

Mosler described the students as "mid-level distributors" who were selling more than a person might buy for personal use.

He identified Phi Kappa Psi and Theta Chi as the two fraternities involved. In the latter case, firearms were found in the house, he said.

The firearms included semiautomatic 9 mm or .40-caliber handguns and a rifle, Mosler said.

He said the students face charges that include possession for sale and sale of cocaine, ecstasy and marijuana.

DEA agents infiltrated several student drug distribution cells and made more than 130 drug purchases and seizures, a news release said.

Authorities said they infiltrated seven campus fraternities and found that in some, most of the students were aware of drug dealing by fraternity brothers.

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