A powerful pipe bomb tossed from a speeding auto exploded in the street on upper Wisconsin Avenue late last night, shattering windows in nearby apartment buildings and damaging several parked cars.

There were no injuries in the blast, which occurred shortly before 11 p.m., but a large fragment of the device was thrown through an apartment window at 2800 Wisconsin Ave., narrowly missing a resident there.

Police officials at the scene could suggest no motive for the incident, but noted that the office of the Iran Times newspaper at Wisconsin Avenue and Fulton Street is diagonally across the intersection from the site of the blast.

The Times, a privately owned Persian and English language weekly with a nationwide circulation, was the target of a firebombing in June of last year that caused $50,000 damage.

Times' publisher Javad Khakbaz told a reporter last night he believed that the bombing had nothing to with the newspaper. "Otherwise, why would they throw it across the street?" he asked.

Khakbaz, who declined to discuss the paper's coverage of the present or past Tehran regimes, said he was working late when he heard a loud noise outside that "sounded like someone had blown a tire." The newspaper office was not damaged, he said.

William Reynolds, 61, a retired Voice of America programming official, said he was sitting alone in his second-floor apartment at 2800 Wisconsin when the blast shook the building and a chunk of metal came flying through the window.

Reynolds, who suffers from a heart ailment, said he was "very startled," and shaken. He called police immediately, he said, then took a heart pill. Police said they recovered a 7-to 8-inch fragment of metal pipe from Reynolds' apartment.

Investigators last night broadcast a description of the car, which they said was a blue sedan occupied by two men, and possibly bearing New Jersey license plates.