Louisiana 'ambush' kills 2 deputies, wounds 2

• NEW: Two of the deputies were off duty
• NEW: Two suspects are in custody and one is still at large, a police spokeswoman says
• Two sheriff's deputies are dead, two others are in the hospital

(CNN) -- Two Louisiana sheriff's deputies died and two others were wounded early Thursday in a shooting outside a steel plant, state police said.

Two suspects are in custody and one remains on the loose, according to state police Trooper Melissa Matey.

Numerous state police SWAT teams, helicopters and troopers were involved in the search for the remaining suspect, Louisiana State Police said.

Matey said two of the deputies with the St. John the Baptist Parish Sheriff's Office were working an off-duty job, while two others were on duty.

At least some of the deputies, whose identities have not yet been released, were on traffic duty at the Bayou Steel Plant in LaPlace when the shootings happened in the parking lot around 5 a.m. (6 a.m. ET), according to State Police Sgt. Ann Dusang.

She initially said the deputies had been ambushed, but Matey later backed off that assertion.

"Right now we're going to say they had an encounter. We're not exactly sure if they were ambushed," she said.

The two wounded officers have been hospitalized, Dusang said.