SAN DIEGO - The weekend beating deaths of three young San Diegans and a Mexican friend in Tijuana may stemmed from an unpaid drug debt, Mexican police sources told FOX 5 San Diego.

According to a press release from the attorney general's office in Tijuana, two men, and two women were found dead inside a cherry-colored mini-van in the eastern Tijuana community of Valle Dorado early Saturday afternoon. The bodies showed signs of beating and torture and were wrapped in blankets, according to Tijuana authorities

Three of the victims were from San Diego, according to family and friends. Family members didn't want to speak on camera, but they told FOX 5 that two of the victims went to Southwest High School. The sources said Luis Antonio Games, 21, and Oscar Jorge Garcia Cota, 23, attended the school, and Briana Hernandez Aguilera, 19, attended Chula Vista High School.

Sign up for FOX5 Breaking News alerts

The fourth victim, Carmen Jimena Ramos Chavez, 20, was a Mexican citizen and a friend of the others.

Families of the San Diego victims mourned the deaths at the Glen Abbey Memorial Park in Bonita Vista, Wednesday afternoon. Family and friends of the victims would not comment on the deaths.

Sources also told FOX 5 that drugs may have played a role in the deaths. In particular, cocaine may have been involved. Investigators are also looking at a possible relationship one of the victims may have had with someone serving prison time in the U.S. on drug charges.

According to sources close to the Tijuana police, one of the victims may have been involved in a drug deal gone bad and an unpaid debt may have lead to the killings. One of the victims was found with a note attached to the body, sources said, but the contents of the note were not known.

A news conference is scheduled for 11:00 a.m. Thursday in Tijuana to discuss the case.

The group reportedly traveled to Tijuana last Thursday to party in the popular tourist destination Avenida Revolucion.