Baghdad, Iraq (CNN) -- Gunmen stormed an outdoor market Tuesday in northern Iraq, killing seven people and robbing several jewelry stores, police said.
The violent robbery happened at 5:30 p.m. in central Kirkuk, an oil-rich city about 240 kilometers (150 miles) north of Baghdad.
Eight attackers threw grenades and fired machine guns before fleeing with cash and gold, police in Kirkuk said.
The dead included three police officers, three jewelry shop owners and a bystander, police said.
Iraqi authorities suspect insurgent groups have staged recent robberies to fund their operations.
A car loaded with cash to pay Education Ministry workers was hijacked Monday in central Baghdad, police said. The robbers spared the lives of three people in the car, but they made off with 30 million Iraqi dinar, worth about $25,000.