Three workers at D.C.’s 911 emergency center in Southeast Washington were apparently overcome by fumes on Thursday from a nearby ruptured gas main, according to the Fire Department.

Battalion Chief Brian Lee said an eight-inch main broke on the grounds of St. Elizabeth’s Hospital, where a new U.S. Department of Homeland Security complex is under construction. It occurred about 11:15 a.m. The cause of the break is under investigation.

No injuries were reported at the hospital site, Lee said, but three employees at Office of Unified Communications, which is across the street in the 2700 block of Martin Luther King Jr. Blvd. SE, complained of fumes wafting into the building.

Lee said the three workers were taken to an area hospital for evaluation. The Unified Communications Center houses the city’s 911 emergency operators and dispatchers. Lee said 911 service was not affected.