A 7-year-old girl was pulled unconscious from the bottom of a crowded District pool Monday by another swimmer and had to be resuscitated by pool staff members, said officials and witnesses.

The incident rattled swimmers and raised concerns about pool safety on a sweltering Labor Day afternoon, the last day of the season for Langdon Park Pool in Northeast Washington.

A D.C. Fire and Emergency Medical Services crew was called to the pool shortly after 4 p.m. for a report of a possible drowning, department spokesman Vito Maggiolo said. By the time paramedics arrived, the girl was “conscious and alert and breathing,” according to Maggiolo, who attributed her rescue to “some extraordinary resuscitation efforts on the part of pool staff.” The girl was evaluated and taken to a hospital, the fire department said.

The Department of Parks and Recreation said when the girl was found unresponsive, lifeguards surrounded her and began providing emergency care, in accordance with the facility’s emergency action plan.

“The D.C. Department of Parks and Recreation’s top priority is to ensure that our guests are safe,” Director Keith A. Anderson said.

But in an interview Monday, Shawn Zeller, a witness who had called 911, raised concerns that the full-capacity pool was not adequately monitored by lifeguards, potentially contributing to the incident. The department confirmed Monday evening that it was looking into that complaint.

Shortly after arriving at the pool with his family Monday, Zeller, 43, of Brookland noted that both lifeguard chairs — one on the shallow end and another on the deep end — were empty. One lifeguard was walking the deck, he said — swatting flies with his rescue equipment.

After a short break, swimmers were let back in the pool about 4 p.m. Zeller said there was a lifeguard in the chair at the shallow end. A few minutes passed when suddenly, he said, a man screamed and pulled the girl from that end of the pool.

“She was completely lifeless. She had no control over her body. She was limp,” Zeller said.

Three lifeguards converged and one of them began resuscitation efforts.

“The girl jerked back to life,” Zeller said. “And she must have expelled the water. So there was just a palpable sense of relief from everyone at the pool.”

Zeller was alarmed, he said, because the girl was found at the bottom of the pool directly in front of the lifeguard’s chair. Zeller said he called 911.

The incident gave the Northeast resident pause.

“It’s astonishing to me that there were not two lifeguards in both chairs and another lifeguard walking the deck when you’ve got a full-capacity pool on a 95-degree Labor Day,” he said.

The Parks and Recreation Department said that there was no shortage of staffers at the pool Monday afternoon and that lifeguards followed the action plan as far as officials knew. Anderson said the department will look into “the entire matter.”