Washington ? FBI agents and police raided three apartments in New York City before dawn Monday during an investigation of a man suspected of being an al-Qaida associate.

The searches came after the man, who was under surveillance for possible links to the terror network, visited New York City over the weekend and left the area, Rep. Peter King, R-N.Y., said after receiving a briefing on the operation from federal law enforcement officials Monday.

Sen. Charles Schumer, D-N.Y., who also was briefed Monday, said a terrorist attack was not believed to be imminent. He added that the law enforcement action was unrelated to President Barack Obama’s visit to the city Monday.

New York Police Department spokesman Paul Browne confirmed that searches were conducted in the borough of Queens by agents of a joint terrorism task force.

Residents on Monday described officers armed with search warrants swarming their immigrant neighborhood about 2:30 a.m. One, Afghanistan native Akbari Amanullah, said when he arrived home from work afterward, he was told that one of his roommates had been hauled away.

No arrests were announced. Neither the FBI nor the NYPD would discuss the whereabouts of the al-Qaida suspect or whether anyone was being held for questioning in New York.

A White House spokesman said Obama, who spoke on Wall Street on Monday, had been briefed on the investigation.

Two U.S. intelligence officials, who requested anonymity because they were not authorized to discuss the case publicly, said the target of any purported attack — or who would carry it out — remained unclear.

Authorities have not found any weapons ready for use that would indicate an attack was imminent, they said. Nevertheless, one of the officials called the threat very real and emphasized the urgency of it.