Updated

A fight at a Baltimore nightclub spilled onto the street early Sunday and led to an eruption of gunfire that killed a police officer and another man and left four people hurt, police said.

One of those wounded also was a police officer, who was shot in the leg, said police spokesman Anthony Guglielmi. Investigators were trying to determine if officers may have fired on a fellow officer whose badge and other identifying markings came off his uniform during the scuffle, he said.

No arrests have been made, but dozens of people were being questioned, Guglielmi said.

"This is an absolutely horrible incident ... I prayed we would never lose another officer, but here we are again," Mayor Stephanie Rawlings-Blake said. An off-duty Baltimore detective was killed in October when he was hit in the head during an argument over a parking space.

Authorities said officers arrived at the Select Lounge to find a large fight and called for backup. Investigators still weren't sure if anyone besides officers had fired their weapons.

"It was a pretty significant fight from what we understand. A large fight and a number of officers responded," Guglielmi told The Associated Press. "It ultimately spilled outside into the parking lot."

The police spokesman said the dead officer was 33 and an eight-year veteran of the department but said he likely wouldn't be identified until Monday. He also did not give the name of the other male victim.

Guglielmi said the second officer was shot in a leg and was expected to recover. The others wounded also were not identified, but the spokesman said they were in their 20s.

Meanwhile, investigators were at the club trying to piece together events.

"We have a lot of ground to cover, a lot of people to talk to," he said.

Guglielmi said no off-duty Baltimore officers were working security at the club, nor were any in the club. He said he did not know if the club had its own security staff.

At dawn Sunday, police tape surrounded the block of Select Lounge. No one answered when a reporter knocked on the door and police asked a reporter and photographer to leave.

Police tape also surrounded a parking lot containing about 25 cars and lay in the foyer of the club. The club is in a mixed industrial and residential area not far from the hospital where victims had been taken. It is next to a car wash.

A valet parking sign for the club was knocked down, but there were no readily apparent signs of shots fired.

In the parking lot next to the club, police crime lab technicians marked shell casings.

The club's website describes it as having a sleek, modern design and "catering to a professional, upscale crowd."

Sunday wasn't the first time the city's nightlife has been rocked by shootings. In March, two people were shot outside the Velvet Rope nightclub when a fight inside the club spilled onto the street.

And on June 5, off-duty police officer Gahiji A. Tshamba was out in a neighborhood known for its nightlife when authorities say he shot and killed an unarmed Iraq war veteran. Police say Tshamba and Tyrone Brown had gotten into a heated argument when Tshamba shot Brown 12 times with his department-issued Glock handgun. Tshamba has been charged with murder.