BAGHDAD -- A double suicide bombing devastated a cafe packed with young people in northwestern Iraq on Thursday, killing at least 21 people, officials said, in the latest attack against a minority community.
The blast capped a deadly week in which nearly 150 people have been killed in bombings concentrated near the volatile northern city of Mosul and Baghdad, heightening fears that Sunni insurgents are stepping up efforts to stoke ethnic and sectarian tensions.
Thursday's attack occurred shortly after 5 p.m. in Sinjar, a city dominated by members of the Kurdish-speaking Yazidi religious group that is concentrated near the Syrian border.
It came two years after a village near Sinjar was hit by one of the worst insurgent attacks since the 2003 U.S. invasion. Four suicide truck bombers exploded nearly simultaneously in Qahataniya on Aug. 14, 2007, killing as many as 500 Yazidis.
The bombers detonated their explosives Thursday inside the Ayoub cafe as the popular sunset destination was packed with people drinking tea and playing dominoes.
City officials imposed a curfew and said some of the most seriously wounded were evacuated to hospitals in the nearby semiautonomous Kurdish region.
"What has happened this afternoon is a catastrophe that hit our city," said municipal council member Meiysar Subhi. "Young people were murdered while they were just trying to have a nice time."
The attack killed 21 people, including an Egyptian resident, and wounded 32, said the director of Sinjar hospital, Dr. Kifah Mahmoud.
The top commander of U.S. forces in northern Iraq, Army Maj. Gen. Robert Caslen, said Tuesday that recent attacks show the resilience of al-Qaida in Iraq and other Sunni insurgents despite numerous military operations against them.
Tensions are especially acute along the sensitive fault line of territory disputed by Kurds and Arabs where the Yazidis live. Kurdish checkpoints guard entrances to Sinjar, and the city's mayor, Dakhil Qassim Hassoun, recently called for it to be incorporated into the nearby semiautonomous Kurdish territory.
Several top U.S. defense officials have identified the split between Iraq's majority Arabs and the Kurdish minority as probably a greater long-term threat to Iraq's stability than the more familiar Sunni-Shiite conflict.
They have warned that conflict between the two groups over land and oil could explode into a new front in the Iraq conflict even as overall levels of violence decline -- a dangerous prospect as U.S. forces prepare to withdraw by the end of 2011. Tensions also have been rising ahead of national elections scheduled for January.
The competition between Arabs and Kurds could lead to "an ethnic, lethal-force engagement," Caslen told reporters, but added he was encouraged by political movement on both sides.
Addressing the recent spasm of violence, Caslen said al-Qaida is using the new attacks to draw attention but so far has not been able to provoke a large-scale sectarian retaliation.
Caslen said the number of insurgent attacks has dropped in Mosul since the handover of control of the city to Iraqi forces on June 30. Weekly attacks averaged 42 before the handover. They now average 29, Caslen said. At the same time, high-profile attacks and attacks on Iraqi security forces are up, producing a higher number of casualties, he said.
Bombers in the area surrounding Mosul have mainly targeted ethnic minorities, indicating that insurgents are seeking out vulnerable, relatively unprotected targets to maximize casualties as the strapped Iraqi army focuses its efforts on more central areas.
Bombings struck mainly Shiite communities on the fringes of Mosul last Friday and Monday, targeting a mosque used by Shiite Turkomen and a Shabak community.
Baghdad also has faced a spate of high-profile attacks.
A motorcycle bomb exploded late Thursday near a restaurant in a Shiite enclave in southern Baghdad, killing at least two civilians and wounding 10 others, police said.
Associated Press Writer Sameer N. Yacoub contributed to this report.