Bullet Fired Near White House Pierced Window : Security: Tests show one weapon was used to discharge four shots. Investigators have no suspect, don’t know whether the attack was intentional.

One of the bullets fired in the direction of the White House by an unknown gunman penetrated a window and landed in the State Dining Room, one floor below the President’s residential quarters, the Secret Service said Sunday.

Another bullet fired early Saturday morning was found beneath a Christmas tree outside the White House diplomatic entrance.

Investigators continued to puzzle over the shooting, saying they have no suspects and no knowledge of whether the bullets, apparently fired from south of the executive mansion, were deliberately aimed at the White House or landed there inadvertently.

All four of the 9-millimeter bullets found by investigators were fired from the same weapon, according to a preliminary ballistics examination. Additional tests to determine the type of weapon were to be conducted today.

With their search completed, investigators said they believe that all bullets on the White House grounds have been found. Secret Service agents reported hearing just four shots, although other witnesses said they heard six.

No one was hurt in the shooting, but the Secret Service has beefed up security for the President.

The bullet hole in the State Dining Room window was concealed by a Christmas wreath and was not discovered until late Saturday afternoon, said Secret Service spokesman Carl Meyer. The room was not being used at the time of the shooting, about 2:05 a.m. EST Saturday.

By the time the bullet entered the room, it had traveled a considerable distance and was relatively harmless, Meyer said.

Although the shooter’s location has not been determined precisely, it appears the gun could have been fired from Constitution Avenue, about 300 yards from the White House, he said.

“All the velocity of the bullet had been spent,” Meyer said. “It was like a pebble going through the window.”

The other two bullets were found on a White House driveway and on the first-floor balcony on the south side of the building.

Some Secret Service and White House officials, including Chief of Staff Leon E. Panetta, have said the shooting might have been the kind of random violence that has been plaguing Washington.

“Whether it was a drive-by shooting, or two cars firing at each other, or somebody coming out of a bar, or firing shots in the air, we don’t know,” Meyer said.

Undaunted by the shooting, President Clinton maintained his Sunday routine, attending church with First Lady Hillary Rodham Clinton to watch his daughter, Chelsea, perform in a skit, then going out for a round of golf across the Potomac River in Virginia.

Security at the church, however, was noticeably tighter.

The weekend shooting will be included in a Treasury Department report on White House security that is scheduled for release next month. The report was commissioned after a September incident in which a despondent young pilot crashed a small plane on the South Lawn, killing himself.

The report will also address an October shooting in which a gunman walked up to the Pennsylvania Avenue fence and fired at the White House with a semiautomatic weapon. Several bullets hit the mansion before the gunman was tackled by bystanders.