This Mystery Enough to Shake Them Up : Crime: Tenants are irritated by abandoned trunks. One piece of luggage is even kicked. Police find they contain arms and explosives.

The two large black steamer trunks stood blocking part of the second-floor hallway of the five-story apartment building on Manhattan’s Upper East Side.

As days passed, tenants regarded them as a nuisance. One even kicked the luggage in anger.

In retrospect, that was not a good idea.

When the luggage was opened late Friday, police found 20 automatic weapons, 2 shotguns, 17 silencers, 3 walkie-talkies, 3 large bags of ammunition, assorted explosives, 4 electronic devices, a bullet proof vest, detonators and scales.

The bomb squad ordered the building evacuated, and police told its superintendent, George Nunes, 35, that if the explosives had gone off, the 32-apartment structure would have been leveled.

On Saturday, FBI agents wearing white surgical gloves dusted the apartment believed to be the one the trunks came from, and authorities wondered if they had stumbled across the tracks of international terrorists.

Police said the apartment’s regular tenant had rented the dwelling last February to a woman described as 18 to 20 years old.

“When the person failed to pay the rent, the resident moved back in and moved the steamer trunks,” a police spokeswoman said.

Police said the regular tenant eventually got around to having the trunks opened, and called authorities.

Emergency squad personnel cleared most of one block of East 75th Street and, wary of setting off explosives, warned residents of the building not to switch television channels, not to turn on any appliances and not to use the elevator as they were evacuated, Nunes said.

He said several weeks ago, three men came to the apartment house searching for the subtenant. One of the men showed a detective’s badge. When the woman was not found, the men departed and did not return.

Standing in the lobby on Saturday, the building’s superintendent described the woman who had rented the apartment from the regular tenant as a dark-haired “youthful” white woman with hazel eyes.

Nunes said she spoke with a British accent. “She was polite,” he said, but he could not give any further information.

Shaken residents of the building said they were ordered out of their homes by police at 8:30 p.m. Friday and were not allowed back into their apartments until about 1:20 a.m. Saturday.

One apartment dweller on the second floor, who declined to give her name, said a neighbor had become so annoyed by the presence of the big black steamer trunks in the hallway that he had begun to kick the luggage.

“We all got sick at looking at them,” the woman said.

A reporter who knocked on the door of apartment 2-F in the building found FBI agents wearing surgical gloves dusting for fingerprints.

The explosives were taken to the police firing range to be detonated. The weapons were given to a joint FBI-police anti-terrorist task force to be checked for fingerprints and to determine if any serial numbers could be traced.

The police spokeswoman said the anti-terrorist task force was in charge of the investigation.