Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

Several U.S. service members were treated for concussions after Iran launched ballistic missiles earlier this month in Iraq in retaliation for the U.S. killing of a top Iranian commander, military officials said Thursday.

"While no U.S. service members were killed in the Jan. 8 Iranian attack ... several were treated for concussion symptoms from the blast and are still being assessed," Capt. Bill Urban, spokesman for U.S. Central Command, said in a statement.

"All personnel in the vicinity of a blast are screened for traumatic brain injury, and if deemed appropriate are transported to a higher level of care," Urban said.

In the days after the attack, 11 service members have been transported to two hospitals, in Germany and Kuwait, for follow-up screening, Urban said.

He said that the service members were expected to return to Iraq following screening.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

The damage at Ain al-Asad military airbase housing US and other foreign troops in the western Iraqi province of Anbar, Iraq on Jan. 13, 2020. Ayman Henna / AFP - Getty Images

The day after the missile strikes, President Donald Trump said that no American or Iraqi lives were lost because of precautions that had been taken, the dispersal of forces "and an early warning system that worked very well." The president also said then that no Americans were harmed.

The Centers for Disease Control and Prevention says that while some symptoms of traumatic brain injury, which include concussions, can appear right away, others may not be noticed for days or months after the injury.

Download the NBC News app for breaking news and politics

Iran launched ballistic missiles against two bases in Iraq that house U.S. forces, including the Ain al-Asad base about 110 miles northwest of Baghdad, on Jan. 8 as retaliation for a drone strike that killed Gen. Qassem Soleimani, commander of Iran’s secretive Quds Force, and another man who is said to be the deputy of militias in Iraq.

Hours after the ballistic missile launch in Iraq, Iran’s military unintentionally shot down a Ukrainian passenger jet that had taken off from Tehran’s airport.

All 176 people aboard Ukraine International Airlines Flight PS752 were killed, including many Iranians and Canadians.

Iranian officials blamed "human error," and Iranian President Hassan Rouhani has called it a "disastrous mistake."

Initially, Iranian officials soon said that mechanical failure was suspected. Iran's foreign minister this week acknowledged that people "were lied to" for days.

The shootdown sparked protests in Iran.

Iran's judiciary said this week that an undisclosed number of suspects involved in the accidental downing of the plane had been arrested.