A Fairfax County psychiatrist was critically injured and two others were hurt in a Mount Vernon medical office building yesterday afternoon when a mailed package exploded in the psychiatrist's face, fire officials said.

Paul J. Peckar, 50, was found screaming with his clothes on fire shortly before 1 p.m. by office workers who frantically poured water on him to extinguish the flames.

Peckar, of the 8400 block of Riverside Road in the Mount Vernon area, was taken by helicopter to Washington Hospital Center, where he underwent surgery for internal injuries from the blast, fire officials said. He also suffered severe burns over at least 30 percent of his body, officials said.

As of late yesterday afternoon, local and federal investigators had no suspect or motive in the bombing, which occurred in the Sherwood Hall Medical Center in the 2600 block of Sherwood Hall Lane east of Route 1.

In an unrelated incident Dec. 22 in Hagerstown, Md., Circuit Court Judge John P. Corderman suffered injuries to his groin, hand and eardrum in a blast from a bomb sent through the mail.

In addition, a wealthy Montgomery County landowner was injured slightly when a pipe bomb blew up in her car in March. There was no indication that any of the incidents were related.

A spokesman for the U.S. Postal Inspection Service, which took charge of the investigation, said the bomb was delivered about 12:30 p.m. and exploded about 25 minutes later.

Investigators said the package arrived stamped "Priority," meaning that it was mailed first class and weighed at least 12 ounces.

Jennifer Ocean, an 18-year-old employee in a dermatologist's office on Peckar's floor, said she "heard this big bang and all this dust came down from the ceiling."

Ocean said that when she opened the door to Peckar's office, she saw Peckar "in flames. He was black with smoke and he was screaming, 'There's another one, there's another one.' " Fairfax police bomb specialists searched Peckar's office for a second bomb, but determined after 20-minutes that there was none.

Marion Jordan, director of the hospital's burn center, said Peckar's prognosis is guarded.

"He is very, very critically injured with multiple sites of injury," Jordan said. Peckar's burns will leave him highly vulnerable to infection in the next two to three weeks, Jordan said.

Also injured in the incident was Valerie Ahmed, 52, according to investigators. Ahmed, whose address was withheld, suffered burns on the legs and face and was being treated at Mount Vernon Hospital across the street from the medical building, according to fire officials.

Mark Appleton, a podiatrist who worked in another office in the building, was treated for smoke inhalation at the hospital and released. Appleton, 38, of the 3100 block of Cantrell Lane in Fairfax, was visiting colleagues on the third floor when the bomb exploded.

In a phone interview, Appleton said he ran to a nearby bathroom, filled a garbage can with water and poured it over Peckar.

Andrea Pessoney, an employee down the hall from Peckar's office, said she stayed by Peckar's side until emergency teams arrived.

"He said over and over again, 'I don't know who could have done this,' " Pessoney said.

Peckar said he "opened the package and it exploded," said Ronald Ocean, a general surgeon who also came to the psychiatrist's aid.

Peckar, who did his residency at St. Elizabeths Hospital in the District and has worked with the criminally insane, opened his private practice in the Sherwood Hall Center about four years ago, according to friends and family. He has no partners.

Peckar recently was appointed to the Northern Virginia chapter of the Washington Psychiatric Society, said Joseph J. Palombi, chairman of the Northern Virginia chapter.

"It's a shame. My first reaction is one of horror," said Palombi, who described Peckar as "astute" and "contemplative."

Charles Wheeler, Peckar's brother-in-law, said he knew of no threats against Peckar's life. "I'm just as surprised as anyone else is," Wheeler said on the steps of the Peckars' two-story home a mile from the medical building.

Wheeler, who was notified about the incident at his Riggs National Bank office, said Peckar has three children, ages 4, 9 and 10.

Fairfax County Supervisor Gerald Hyland described Peckar, a friend and former neighbor, as an "absolutely super fellow, the last person in the world that you would think somebody would do this to."

The damage and fire from the blast were confined largely to Peckar's office, with only smoke, water and minor ceiling damage to nearby office space, according to investigators.

Several of the estimated 75 people evacuated from the building said they felt a jolt, then smelled smoke and heard screams.

Pessoney described the explosion as "intense," adding, "It was like a crane had come through the side of the building."

Staff writers Pamela Babcock, DeNeen L. Brown, D'Vera Cohn, Thomas Heath and Avis Thomas-Lester contributed to this report.