Binghamton, NY -- The police chief of Binghamton, N.Y., said the gunman who killed 13 people at an immigrant community center there wore body armor during the attack.

Police Chief Joseph Zikuski said Saturday that the gunman's name was Jiverly Wong and used the name Jiverly Voong as an alias. Mr. Zikuski said the man had a permit for two handguns and wore body armor, indicating he was prepared for a confrontation with police.

Mr. Zikuski said that instead Mr. Wong committed suicide at the end of his attack on the American Civic Association.

As many as 37 people were injured in the attack, including four who were hospitalized in critical condition. The victims were employees of the center and students studying to become citizens, officials said. One survivor, a receptionist who had been shot in the stomach, crawled under a desk and called police to the scene.

The violence in this upstate New York city followed a spate of mass shootings around the country, one of which occurred Sunday when Robert Stewart, 45, shot and killed eight people at Pinelake Health and Rehab in Carthage, N.C., before a police officer shot him.

President Barack Obama, traveling in Europe, called the events in Binghamton an "act of senseless violence," and said he and his wife, Michelle, are praying for the victims, their families and the people of Binghamton.

As police worked to identify victims, family members waited anxiously for word of their loved ones.

Not long before 8 p.m., Omri Yigal, 53 years old, emerged from the Catholic Charities of Broome County where he had been waiting for word about his wife, who had been taking English classes at the civic association. "I just want to locate Doris," he said. "And we'll just go from there."

The attack began before 10:30 a.m. Friday when the gunman drove to the back of the Civic Association, a nonprofit organization that helps immigrants and refugees learn English and prepare for the exam to become U.S. citizens. Several of the association's clients, which include Vietnamese, Chinese and Eastern Europeans, were likely in class as they had been preparing to take a citizenship test later this month, said Angela Leach, the association's president, who was reached at home in the early afternoon before the extent of the tragedy was known. "I have no idea what could have gone on," she said.

The gunman immediately turned his weapons on two receptionists. One, who was shot in the head, died, said U.S. Rep. Maurice Hinchey, a Democrat whose 22nd district includes Binghamton. The gunman then strode into a nearby classroom and shot about 13 people, Mr. Zikuski said.

About 26 students, hearing gunshots, ran for cover in the basement, hiding in the boiler room, the chief said; 911 dispatchers advised them how to barricade doors. "We had to repeatedly assure them, do not come out," he said. Some of the students did not know English, but the chief said that did not hinder the rescue.

Once SWAT team members entered the building, they walked from room to room, finding survivors and leading them out the door. The police said they wanted to be cautious before they identified the gunman. They do, however, know who borrowed the vehicle that was blocking the building's rear.

A spokeswoman at the nearby Wilson Medical Center said the hospital had three patients taken there from the shooting site, one male and two females, ranging in age from 20 to 60. All had gunshot wounds and two were in surgery. Their conditions ranged from stable to critical, she said.

The downtown area of this city of about 47,000 was transformed into an emergency staging area. Police vehicles blocked roadways, ambulances lined up in the parking lot of the nearby First Congregational Church and SWAT-team members stood atop adjacent buildings and crouched behind trees.

Officers climbed onto the roof of an old firehouse that is the home of Pennie Kerber, 72. Ms. Kerber said she was holed up in the building for the better part of the day, afraid that gunfire could erupt. Her husband was stuck at the bowling alley, unable to return home because police cars were blockading the street. Ms. Kerber said she saw one man on a stretcher being carried out of the Civic Association. "It's nerve-wracking," she said.

Catholic Charities in Binghamton opened its doors to about 50 people whose family members had been inside the association headquarters. "Our staff is trained with counseling and can respond right away in a crisis," a spokeswoman for Catholic Charities from the Diocese of Syracuse said.

In the early evening, spectators gathered about half a block from the association building. Sammie Silas, 48, said: "If this happens over here, it could happen anywhere else."

—Suzanne Sataline, Dionne Searcey, Matt Phillips and the Associated Press contributed to this article.