The AP is reporting:

The investigation into an alleged plot to bomb the city’s subway moved forward on several fronts Friday as a third suspect was arrested in Iraq and authorities looked into whether a fourth person had traveled to New York as part of the scheme, officials said.

A law enforcement official familiar with the case said the man’s trip to New York was described by an informant who had spent time in Afghanistan and proved reliable in past investigations.

“He’s been a source of multiple correct information in the past,” the official said, speaking on condition of anonymity because of the continuing investigation. “Does that mean a fourth person he identified is in fact in New York? We don’t know that.”

The official added that authorities had not confirmed whether the fourth man even exists.

Another AP report:

Mayor Michael Bloomberg and his police chief insisted Friday they did the right thing by going public with a terrorist threat to bomb the New York subway, brushing aside suggestions from Washington that they overreacted to information of dubious credibility.

“If I’m going to make a mistake, you can rest assured it is on the side of being cautious,” Bloomberg said.

You go, boy Bloomberg. Arrests have been made. How does preparing for another atrocity count as “overreacting?”

And…

U.S. forces in Iraq arrested two suspected plotters who had been under close surveillance until Thursday morning, the law enforcement official in New York said. A third suspect escaped but was captured Friday.

Those arrested had received explosives training in Afghanistan, the law enforcement official said. They had planned to travel through Syria to New York, then meet with operatives to carry out the bombings, according to the official. The official said that the threat was “specific to place,” and that the window for the attack ran from Friday through at least the weekend.

A federal official said one of the suspects arrested in Iraq apparently told interrogators that more than a dozen people were involved in the plot, and that they were of various nationalities, including Afghans, Syrians and Iraqis. The official spoke on condition of anonymity because the investigation is continuing.