NEW YORK: While members of an Islamic cultural center gathered for a Sunday evening dinner, a Molotov cocktail hurled by an unknown assailant and made from a Starbucks bottle burst and shattered against the center's main entrance. Another was thrown at the sign for the center's school.

It was one of a string of suspected arson attacks that police were investigating on Monday as possible bias crimes and trying to determine whether the incidents were linked. No arrests have been made.

Structural damage to the Imam Al-Khoei Foundation was minimal, but some members of the center were emotionally shaken, the assistant imam said. About 80 worshippers were there when the firebomb was set off at 8:44 p.m., the third in the series of suspected arson attacks in Queens on Sunday night.

"We were very surprised," assistant Imam Maan Al-Sahlani said. "This has never happened here before."

The decades-old foundation is among the foremost Muslim institutions in New York, with branches around the world, he said. Named for one of the most influential Shiite scholars, it promotes work in development, human rights and minority rights as a general consultant to the Economic and Social Council of the United Nations.

The center also has a full, accredited school that resumes Tuesday after holiday break, and some parents were concerned about the attack, Al-Sahlani said. The sprawling complex has two minarets rising high with the Van Wyck Expressway as a backdrop. On Monday, the concrete overhang outside the main entrance was blackened from smoke damage and there was minor damage to the area near the sign, as yellow police tape fluttered.

But Al-Sahlani, 36, dressed in traditional clerics' robes, said the center was working with authorities and trying to move forward. Worshippers prayed and milled around, and the front doors were wide open.

"This is America," he said. "And we must continue to love one another."

Other targeted locations were more substantially damaged. No one was injured in the four attacks. Police said at least three Molotov cocktails were thrown, though some did not explode.

The first hit at 8 p.m., when a bottle was thrown at a counter at a corner store known as a bodega.

Ten minutes later, a nearby house was damaged in a fire that erupted when a possible firebomb smashed through glass; it took 65 firefighters 40 minutes to bring the blaze under control, authorities said. The home was badly damaged.

At 8:44 p.m., the Islamic center was targeted.

And at 10:14 p.m., two bottles were thrown - but did not explode - at a house police said was used for Hindu worship services.

Police said possible suspects were believed to have fled the scenes of the third and fourth attacks. They were looking at surveillance video obtained from the bodega and the attack on one of the houses.

Meanwhile, political leaders spoke out against the incidents. Mayor Michael Bloomberg said New York Police Department hate crimes unit detectives were working with precinct detectives and looking into whether there were any connections to incidents outside the city.

Gov. Andrew Cuomo and the Council on American-Islamic Relations condemned the violence.

"The four reported attacks on Sunday night go against everything we stand for as New Yorkers and Americans," Cuomo said in a statement. "Attacks such as this have no place in our open and inclusive society."

CAIR called on police and Muslim institutions to step up security measures around mosques.

Ibrahim Hooper, a spokesman for the advocacy group, said CAIR recently called on the FBI to investigate threats targeting mosques posted on an anti-Islam blog called "Bare Naked Islam."

One comment on the site read: "Throw 10 Molotov cocktails into these mosques and burn them down," according to Hooper. By Monday, the comment appeared to have been taken down by blog operator WordPress.com.

The council noted that in the past year, numerous mosques or mosque construction sites around the country have been targeted by arson, vandalism or threats.