Two college students were found dead inside a large, deflated helium balloon after apparently pulling it down and crawling inside it, officials said. The deaths of Jason Ackerman and Sara Rydman, both 21, appear to be accidental, Hillsborough County Sheriff's Maj. Bob Schrader said. Their bodies were found Saturday partially inside a deflated helium balloon at the entrance of a condominium complex a few miles north of Tampa. The 8-foot-diameter balloon was used to advertise the complex. "It was more a fun thing they thought they were doing," said Linda Rydman, whose daughter was found dead. "You know how you blow up the balloon and suck the helium." The county medical examiner said Sunday that the cause of death won't be released for six weeks, until toxicology results come back. Inhaling helium can quickly lead to brain damage and death from lack of oxygen, according to the Compressed Gas Association, which develops safety standards in the gas industry.