Juan Ramos and Adain Gutierrez of COCAT Restoration & Reconstruction work at Chelsea Park Village Apartments in Aurora, CO ,Saturday, July 16, 2011. (THE DENVER POST | Craig F. Walker)

A suspected chemical suicide forced the evacuation of an apartment complex, one of a small but growing number of such cases nationwide.

Residents from 36 units at the Chelsea Park Village apartments had to leave their homes overnight during the investigation and cleanup.

All were allowed home by 4 p.m. Saturday.

Police and firefighters were called to 12079 E. Archer Place about 4 p.m. Friday, Fire Capt. Allen Robnett said.

When they arrived, they found a note taped to a bathroom door saying hazardous materials had been used and to call 911. The building was evacuated, and when the hazardous materials team entered the apartment, members found the body of a woman in the sealed bathroom, Robnett said.

Police are investigating the scene as a possible chemical suicide, said Detective Bob Friel, a police spokesman.

The note posted on the door fits the pattern of a chemical suicide.

Directions for the chemical suicide method, first publicized in Japan, can be found on the Internet.

According to The New York Times, more than 2,000 people have taken their own lives by what the Japanese call “detergent suicide.”

The common link is the use of lethal household chemicals in an enclosed space, usually a car, and the posting of signs to warn that there is a potential for a larger catastrophe if the poisons are released into the area.

The Times reported last month that there have been 72 chemical suicides in the U.S. since 2008. At least 80 percent of them caused injuries to people other than the person committing suicide: police officers, emergency workers or bystanders.

Last year, there were 36 chemical suicides in the U.S., the Times reported, and at least 27 this year as of early June.

After one such incident in June, Los Angeles county coroner’s spokesman Ed Winter told The Associated Press that the usual mixture of chemicals, which includes hydrogen sulfide, is incredibly lethal.

“One big breath, and boom. That’s it,” Winter said.

The Arapahoe County coroner’s office removed the body about 3 p.m. Saturday after the area had been decontaminated. The identity of the woman has not been released.

Residents at the complex had complained about an odd smell coming from the building. A maintenance manager went to investigate the scene and called 911 when he saw the note.

Aurora officials did not have a toxicology report available Saturday night, and an autopsy had not been completed.

Police officer Dave Wilson was guarding the building while CO-CAT Restoration and Reconstruction decontaminated the facility.

Wilson said he could not comment on the investigation, but said there have been memos circulating around the department about how to deal with chemical suicides.

Omar Valera said he and his parents stayed with relatives Friday night after they were told to leave their home.

“It smelled really bad, like rotten eggs, Thursday night,” Valera said.

Residents of neighboring buildings looked on as crews picked up the remaining suits and materials from the hazardous materials team. Some said they, too, smelled sulfur starting late Thursday.

Michael Brown, who lives across from the building, said he first heard that there was a gas leak. He said he sent his children, ages 5 and 6, to his mother’s house because he was worried about what might be lingering in the parking lot from the cleanup.

“There were so many trucks here Friday night, you would have thought a nuclear bomb went off,” he said.