BOISE, Idaho — Air monitoring systems were set up Tuesday to check for low-level nuclear radiation and other harmful contaminants following a powerful weekend blast at a hazardous waste site in Idaho that killed a worker, destroyed a building and damaged other structures, an official said.

Results were not yet available from the monitors installed at the US Ecology site about 50 miles (80 kilometers) south of Boise, said Albert Crawshaw of the Idaho Department of Environmental Quality.

Monitors have also been installed outside the site.

Officials said it's not clear what caused the explosion. US Ecology takes in low-level radioactive waste, but none of the material was believed to be near the explosion on Saturday, Crawshaw said.

The facility also accepts contaminants such as arsenic, lead, zinc, cadmium and other metals. It's also unclear if containers holding any of that hazardous waste were damaged in the explosion.

Some types of waste can emit dangerous gases or create the potential for explosions if they react with other hazardous waste.

The explosion occurred in a building where hazardous waste is treated. Images appear to show the blast blew out the roof and walls, Crawshaw said.

"The building was demolished," he said.

Other buildings at the 200-acre site also sustained damage, and an inspector was examining them to determine if it's safe to enter.

US Ecology converts contaminants to non-hazardous residues, minimizing the long-term risks of disposal. The company then buries the material at the site.

Crawshaw said the company reported that low-level radioactive waste at the site already had been buried at the time of the explosion.

Three workers with the U.S. Environmental Protection Agency are at the site, EPA spokesman Mark MacIntyre said, adding that the cleanup is being led by the company.

"We're there to provide oversight," he said. "If there's anything they need to affect a quick and safe cleanup, we will do that."

US Ecology spokeswoman Ysabel Bilbao said the company had no comment on specific efforts underway at the site.

"At this point, the investigation continues," she said.

The company previously identified Monte "Alex" Green of Grand View, Idaho, as the worker who died in the explosion.

Three other people received treatment for non-life threatening injuries. A total of 15 employees were working when the explosion occurred.

In 2012, US Ecology agreed to pay a $184,400 fine after the EPA said it failed to submit timely reports on toxic chemical releases at the site, according to the agency.