According to initial reports, four of the five injured contractors are US citizens, a defense official told CNN.
The nationality of the dead contractor was not disclosed, although the defense official said that the initial reports suggest that they were not American.
Previously, a statement from the Interior Ministry of the Kurdistan Regional Government said that several rockets had been launched against the city.
The regional government asked residents to stay home while authorities investigated the incident. No group claimed responsibility for the attack. The United States is currently gathering intelligence to try to determine where the rockets were launched from, the defense official said.
The video of the scene showed that at least one of the rockets landed on a busy urban street, sending a cloud of sparks and smoke into the air.
Erbil, which is located in the semi-autonomous region of Kurdistan and hosts US troops, is expected to be one of several cities that Pope Francis will visit in early March on a historic trip to Iraq.
The attack came a day after the Trump administration told Iraqi leaders that it would close the U.S. embassy in Baghdad if Iran-backed militias continued to target American personnel in the country. The threat followed the decision to withdraw thousands of American soldiers from Iraq in September, bringing the total number of 5,200 troops to approximately 3,000. The number was reduced to 2,500 just before President Joe Biden took office. Acting defense secretary at the time, Christopher Miller, said the reduction was in response to “the increased capacity of Iraqi security forces
CNN’s Taylor Barnes contributed to this report.