Authorities are investigating whether the car-and-knife attack at Ohio State University that injured 11 people was an act of terror. The attacker, Abdule Razak Ali Artan, was killed Monday after he drove into a group of pedestrians on campus, then began stabbing people with a butcher knife.

Artan was born in Somalia and was a legal permanent resident of the U.S., according to a U.S. official who was not authorized to discuss the case and spoke to The Associated Press on condition of anonymity. He was a student at Ohio State who had once criticized the media for its portrayal of Muslims.

A law enforcement official who spoke to The Associated Press on condition of anonymity said Artan railed on Facebook against U.S. interference in Muslim lands and warned, "If you want us Muslims to stop carrying lone wolf attacks, then make peace" with the Islamic State group.

The official was briefed on the investigation but wasn't authorized to discuss it publicly.

Here are things to know about Somalis in the U.S.:

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SOMALI DIASPORA

Job opportunities and the relatively low cost of living have drawn Somali immigrants to Columbus, Ohio, which has the second-largest Somali population in the U.S., estimated at anywhere from 13,000 to 40,000.

Minnesota has the nation's largest Somali community, with census numbers putting the population at 57,000, mostly in the Minneapolis-St. Paul area. Somalis began coming to Minnesota in the 1990s after a civil war broke out in Somalia. Other waves of refugees followed and the community prospered, thanks to the state's welcoming social programs.

The community has largely prospered. Somali-owned restaurants, mosques, clothing shops, coffee shops and other businesses are well-established in some Minneapolis neighborhoods, including one dubbed "Little Mogadishu," named after the capital of Somalia.

Large Somali communities are also concentrated in Lewiston and in Portland, Maine, and in the Seattle and Washington, D.C., metro areas.

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TERROR RECRUITING

In the past decade, law enforcement and Somali community leaders around the country have struggled with terrorist groups luring some of its young men overseas. The problem first surfaced in 2007, when more than 20 young men from Minnesota began going to Somalia to join al-Shabab, which is classified as a terror group by the U.S. government. The group wooed young Americans with jihadist videos that appealed to patriotic and religious ideals.

In more recent years, the Islamic State has found recruits in the U.S. Roughly a dozen young men and women from Minnesota's Somali community have left to join militants in Syria, and nine Minnesota men were recently sentenced on terror charges for plotting to join the Islamic State group.

In September, a Somali-American stabbed and injured 10 people at a central Minnesota mall before he was killed by an off-duty police officer. Authorities have said the actions of Dahir Ahmed Adan, 20, suggested he had been radicalized, but the investigation continues. If that attack is ultimately deemed a terrorist act, it would be the first carried out by a Somali on U.S. soil; and Artan's attack at Ohio State would be the second.

Authorities say others have been stopped before carrying out attacks. In Columbus, Abdirahman Sheik Mohamud, a U.S. citizen born in Somalia, awaits trial on charges alleging he received weapons, combat and tactical training in Syria, then returned to the U.S. with a plan to attack a military base or a prison.

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CONCERNS, EFFORTS TO STOP RECRUITING

Federal officials have said one of their biggest fears was that a radicalized American who left the country to join the Islamic State or al-Shabab might return home to carry out attacks on U.S. soil. That was before the Islamic State began urging sympathizers to carry out "lone wolf" attacks in their home countries with whatever weapons they have available. In recent months, authorities have raised concerns about online propaganda that encourages car-and-knife attacks, which are easier to pull off than bombings.

Stopping recruiting has been a high priority in cities with large Somali populations. Law enforcement has invested countless hours in community outreach, and trying to engage youth who may feel disenfranchised or caught between two worlds.

In Portland, Maine, police have hired Somali teens as summer cadets and worked with them through a leadership and esteem program. In nearby Lewiston, police have worked to recruit Somali police officers. Somali community leaders in Columbus meet frequently with federal law enforcement, and a mosque gives youngsters an outlet for their energies.

Minneapolis has been participating in a federal pilot program designed to curb terror recruiting. As part of the pilot, about a half dozen organizations that work with Somali youth received grants for programs including youth sports activities, job opportunities and a program to empower Somali parents.

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COMMUNITY ACTIVISM

Somali and Muslim community activists have been quick to condemn terror attacks wherever they occur, and that's true in the Ohio State case. Leaders of Muslim organizations and mosques in the Columbus area condemned the attacks while cautioning people against jumping to conclusions or blaming a religion or an ethnicity.

After the mall stabbing in St. Cloud, Minnesota, the Somali community was on edge. Jaylani Hussein, the executive director of Council of American-Islamic Relations' Minnesota chapter, said some local Somali-Americans were nervous about being viewed as "guilty by association."

After Monday's attack, he said: "We must not let the act of one individual, no matter what his motive or background, to further divide our community or our nation. ... We have faith in our fellow Americans to do the right thing. This is a very dangerous time to be Muslim or perceived to be Muslim in the United States, and this week must be an opportunity for all Americans to show that they can stand together against violence of all forms."

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Associated Press writer Steve Karnowski contributed to this report.

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Follow Amy Forliti on Twitter: http://www.twitter.com/amyforliti . More of her work can be found at http://bigstory.ap.org/content/amy-forliti.