Two homicide bombers killed at least 21 people and wounded more than 30 in northern Iraq on Thursday, police said.

The coordinated attack took place in a crowded cafe in Sinjar, a city 240 miles northwest of the capital Baghdad, according to Reuters.

The blast occurred shortly after 5 p.m. in Sinjar, a city dominated by members of the Kurdish-speaking Yazidi religious minority 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 homicide truck bombers exploded nearly simultaneously in Qahataniya on Aug. 14, 2007, killing as many as 500 Yazidis.

The Ayoub cafe that was struck Thursday is located in a leafy area near a spring and is a popular sunset destination.

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 director at the Sinjar hospital, Dr. Kifah Mahmoud, said 21 people were killed, including an Egyptian resident, and 32 wounded.

Sinjar Mayor Dakhil Qassim Hassoun said most of the victims were Yazidis.

The bombing was the latest in a week of devastating attacks in the area surrounding the volatile city of Mosul, which the U.S. military has dubbed the last urban stronghold of al-Qaida in Iraq.

Bombers also have targeted minority Shiite Turkomen and Shabaks in recent days, with more than 120 people killed since last Friday.

Baghdad also has faced a spate of high-profile attacks. But the 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.

The bloodshed has raised concerns about the ability of Iraqi forces to protect people as the U.S. military prepares to withdraw its forces by the end of 2011.

The Yazidis live along the sensitive fault line of territory disputed between Kurds and Arabs, with Kurdish checkpoints guarding entrances to Sinjar. U.S. commanders have warned that rising tensions 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.

Ordinary crime also is on the rise in Iraq, with armed robberies targeting jewelry stores, currency exchanges and pawn shops.

A gunfight erupted during an attempted bank heist earlier Thursday in Iraq's capital, as a court official announced that five members of Iraq's presidential guard will go on trial later this month for their alleged roles in a previous heist.

The four gunmen got into a shootout with police as they tried to flee a bank in Baghdad's downtown Karradah district, a police official said.

The gunmen had Interior Ministry identification cards that allowed them access to the bank and once in, forced bank employees into a room at gunpoint while they went on with the robbery, the official said.

The men surrendered after the gunfight, and a female bank employee was later arrested on suspicion of working with the robbers, the official added. He spoke on condition of anonymity because he wasn't authorized to release the information. No one was hurt in the shootout.

The attempted heist comes amid concerns about possible infiltration of criminals and militants among Iraq's security forces. The issue was highlighted following the arrest of five members of Iraq's presidential guard on charges they participated in a pre-dawn robbery that left eight security guards dead.

The men are accused of robbing the state-run Rafidain Bank in Baghdad on July 28 and making off with about $6.9 million.

Warrants have been issued for three other members of the presidential security detail, who also have been implicated in the heist and remain at large, said Abdul-Sattar Bayrkdar, a spokesman for Iraq's Supreme Judicial Council.

He said the trial for the five in custody is set to begin Aug. 23.

Authorities have said the July heist was a rogue act committed by men belonging to the security detail charged with protecting Iraqi officials, and denied speculation they were part of a larger conspiracy to use the money to fund insurgent groups.

The Associated Press contributed to this report.