According to initial reports, four of the five injured contractors are U.S. citizens, a defense official told CNN.
The nationality of the contractor who was killed was not disclosed, but the defense official said the initial reports indicate they were not American.
A statement from the Interior Ministry of the Kurdistan Regional Government said several rockets had been fired at the city.
The local government called on local residents to stay home while authorities investigated the incident. No group claimed responsibility for the attack. The U.S. is currently gathering intelligence to try to determine where the rockets were launched from, the defense official said.
The video of the scene shows at least one of the rockets ending up in a busy urban street, sending a cloud of sparks and smoke into the air.
Erbil, located in the semi-autonomous Kurdistan region and home to US troops, is expected to be one of several cities visiting Pope Francis during a historic trip to Iraq in early March.
The attack came a day after the Trump administration told Iraqi leaders that it would close the US embassy in Baghdad if militias backed by Iran continued to target US personnel in the country. The threat follows the decision to withdraw thousands of US troops from Iraq in September, bringing the total number of 5,200 troops to about 3,000. The number was further reduced to 2,500 shortly before President Joe Biden took office. The then acting secretary of defense, Christopher Miller, said the withdrawal was in response to the ‘increased capabilities of the Iraqi security forces’
Taylor Barnes of CNN contributed to this report.