LOS ANGELES (CBSLA.com) — Two Los Angeles Police Department detectives were injured Tuesday morning during a shooting in the mid-city area, authorities said.

The shooting happened around 4:30 a.m. outside of the LAPD’s Wilshire substation near San Vicente and Venice boulevards, the Los Angeles Fire Department said.

“They were undercover officers working the burglary task force here out of the Wilshire station. They pulled up to the front of the gate and as they were opening the gate, from directly behind them, somebody for some reason opened fire on their car, striking it many times,” Cmdr. Andrew Smith said.

One officer suffered a hand injury and the other suffered a graze wound to his head, but they were able to return fire. They were transported to a local hospital and subsequently released.

The city was placed on tactical alert following the shooting.

Officers detained at least 10 men for questioning but have since cleared them as suspects.

“We’re questioning, going to have the officers that were shot take a look at them,” Smith said.

At least one suspect, who police said fled the scene on foot in a southwesterly direction, was outstanding, officials said. He is described as a black male, 30 to 35 years old with a medium build, facial hair and wearing all black clothing, Chief Charlie Beck said.

About 200 officers from several LAPD divisions, four K-9 units and the Culver City Police Department were assisting in the investigation. The injured deputies were also able to return to the scene of the crime to help.

A motive for the shooting was unknown.

Motorists should avoid the area bordered by Pico, West, Venice and Western boulevards.

Authorities believe Tuesday’s incident was isolated, but are taking extra precaution.

“We’ve supplemented the security at all our police stations in case this was something other than a random act against our officers,” Smith said.

The tactical alert was canceled around 8:30 a.m. and the LAPD’s West Bureau only was placed on a modified tactical alert, according to authorities.