HAMLET, N.C. (AP) _ Screaming workers pounded and kicked locked exit doors as fire swept a chicken processing plant, killing 25 people and injuring 55. The 11-year-old plant had never been inspected.

''A whole lot of people were in one little corner, just pushing, trying to make a hole in the wall,'' said worker Letha Terry. ''I thought I was gone, until a man broke the lock off the door. I thank the Lord I got out, but a whole lot of people got killed.''

The federal worker safety agency was investigating the blaze and also conducted a surprise inspection of another Imperial Food Products plant in Georgia, an official said today.

The blaze Tuesday at the Imperial plant erupted when a hydraulic line ruptured near a 26-foot-long deep-fat fryer and the spilled fluid caught fire, said Charles Dunn, deputy director of the State Bureau of Investigation.

Fire Chief David Fuller and Mayor Abbie Covington would not confirm witnesses' reports that all but one of nine exits were locked or blocked.

''I don't have any evidence of doors being locked,'' Covington said today. ''If we determine that doors were locked, I'm sure there will be some sense of outrage, but I'm not in a position to reach that conclusion.''

Ella Mae Blackstock and other workers said the company kept doors locked ''so people couldn't steal their chickens.''

''Certain doors are locked at certain times,'' said Brad Roe, operations manager and son of plant owner Emmett J. Roe. ''I can't tell you which doors were locked, if any were locked.''

SBI agent Neil Godfrey said the designated fire doors were unlocked, but other exits were impassable, including those closest to the fire. ''Obviously there may be some compliance problems,'' he said.

However, a door with a sign saying ''Fire Door Do Not Block'' was seen padlocked.

Blackened footprints were on one door after the blaze. Some workers could be heard screaming helplessly and eventually perished, witnesses said.

Some victims were found near exits and others were found in a meat locker, where they had fled, Fuller said. About 90 of Imperial Food's 200 employees were in the plant when the fire erupted about 8:30 a.m., the company said.

Authorities said 25 people were killed, and hospitals reported at least 49 injured. The bodies were sent to the State Medical Examiner's Office in Chapel Hill for autopsies; the mayor said most died of smoke inhalation.

''You can tell by the look of the people that it's a tragedy beyond belief,'' Covington said. ''In a small town its always somebody's neighbor or somebody's son.''

One fireman found his father dead, said Joey Jernigan, a town councilman.

A few employees worked the overnight shift cleaning the plant. William English, a supervisor who turned people away from the plant this morning, said the mood among the few workers on duty today was somber.

''It's a real sense of loss when you see some of the (victims') cars still parked out front,'' English said.

Imperial Food is the town's largest employer. Hamlet, in south-central North Carolina, has a population of about 6,900.

The plant, which makes chicken nuggets and marinated chicken breasts sold at fast-food restaurants and grocery stores, was never inspected by the state because there are not enough inspectors, said Charles Jeffress, assistant commissioner of the North Carolina Department of Labor.

The state focuses on plants that have safety complaints, and none had ever been filed against Imperial, he said. The state fire code does not specify how often a plant should be inspected.

In Cumming, Ga., where Imperial Food has another plant, a team from the federal Occupational Safety and Health Administration began an inspection Tuesday night, an OSHA official said today.

The investigation began because of the North Carolina fire, as well as a safety complaint at the Cumming plant, said Jonathan Worrell, assistant area director for OSHA in Atlanta. Worrell would not release details of the investigation or the complaint. He said all OSHA inspections are surprise inspections.

Employees at Imperial Foods headquarters in Atlanta said all company officials who could discuss the two plants were on the scene in North Carolina.

In North Carolina, Dunn of the SBI said maintenance workers had just reconnected the hydraulic line when it ruptured, spraying the flammable fluid onto the floor, he said.

The vapor reached the fryer in the middle of the 30,000-square-foot plant ''and apparently there was a flash and the fire started there,'' he said. Covington said this morning that the SBI has concluded that no criminal activity was involved in the fire.

Worker Carolyn Rainwater said, ''I saw a big puff of black smoke and I started running for the back door.''

A delivery truck was backed up to the loading dock door, but she and others escaped by jumping into the trailer and yelling for the driver to pull away.

''I felt helpless,'' said Sam Breeden, a passerby. ''They were screaming, 'Let me out 3/8' They were beating on the door.''

Breeden helped his sister-in-law, Mattie Fairley, poke her head out a garbage chute to get fresh air. She was hospitalized in stable condition.

Sharon Townsend, another worker, said: ''We were in the bathroom. A man came along and kicked the back door out. That's the only way we got out.''

James Arnold's sister was killed. ''When they have the words 'fire exit' over a door and it's bolted locked, I want to know why,'' he said, tears streaming down his face.

Fuller said he did not know whether a ''state of the art'' fire extinguisher above the fryer, which is supposed to go off automatically, worked. It was installed after a 1983 fire that caused no deaths, he said. There was no sprinkler system at the plant.

Fire damage was limited to the fryer area, although most of the plant was damaged by smoke.

The official number of injured was increased from 49 to 55 this morning. Covington said some people had a delayed reaction to the effects of smoke and sought medical attention late Tuesday.