Shootout leaves 2 sheriff's deputies dead in La.

Updated at 10:53 a.m. ET

(CBS/AP) LAPLACE, La. - Authorities said Thursday two sheriff's deputies were shot and killed while interviewing suspects in an earlier shooting of a deputy in a parking lot west of New Orleans, CBS New Orleans affiliate WWL-TV reports.

St. John the Baptist Parish Sheriff Mike Tregre said the incident began when an officer at the parking lot for contractors at Valero Energy was approached and shot several times by a suspect. That officer was taken to University Hospital and is in surgery but expected to survive, Tregre said.

Working on tips from a civilian and another officer, a vehicle similar to the suspect's was spotted and tracked to a trailer park.

Tregre said that deputies knocked at the door and had two people come outside for an interview about the shooting. At that time, a third suspect exited another door and shot the two officers to death in what he described as an "ambush," he said.

Tregre said he believes there are several suspects in custody, some of whom suffered gunshot wounds. He said he believes officers are in control of the situation and that no suspects are on the loose. He said the public is not believed to be in danger.

"It's been a very difficult day," said an emotional Tregre. "I lost two good officers today."

The parking-lot shooting occurred around 5:30 a.m. in a parking lot used by workers in the area about 20 miles west of New Orleans, near the line between St. Charles and St. John the Baptist parishes. A massive grain port also is nearby.

Bill Day, spokesman for Valero Energy Corp., said the deputies were providing security for an off-site parking lot used by contractors working at the Valero St. Charles Refinery.

Day said operations at the refinery had not been affected. Valero employees were being asked to report to work as normal, unless they park at the lot where the incident took place.

Some other plants in the area were letting non-essential workers in the area leave for the day or were telling them not to report for work as the search continued.