Two American students died at the end of last week after crawling inside a large deflated helium balloon.

According to CBC News the bodies of the students were found on Saturday partially inside a deflated helium balloon at the entrance of a condominium complex near Tampa. The 2.4-metre balloon was being used to advertise the complex.

U.S. Compressed Gas Association has warned that inhaling helium is dangerous because it can quickly lead to brain damage and death from lack of oxygen. The county medical examiner said on Sunday the official cause of death will not be released for six weeks, until toxicology results come back.