U.S. military doctors worked through the night into Thursday stabilizing soldiers and civilians injured in a deadly insurgent attack on a base in northern Iraq (search), a hospital spokeswoman said.

Forty-two soldiers and civilians arrived for treatment Wednesday at the U.S. military's Landstuhl Regional Medical Center (search) in southern Germany with chest wounds, shrapnel wounds, broken bones and burns.

"We've been working around the clock," said Landstuhl spokeswoman Marie Shaw.

With Christmas near, extra doctors working on lighter holiday schedules have been put on standby, told that they need to be able to report to the hospital within two hours if needed. So far, the regular staff has been able to cope with the workload, Shaw said.

"Even our commander went in to surgery last night," she said in a telephone interview.

The hospital was preparing to evacuate 11 patients later Thursday to Brooks Army Medical Center in Texas, which has a burn center.

"They need specialized care," Shaw said.

Landstuhl receives U.S. casualties from all over Iraq and Afghanistan (search), and it was not immediately clear how many of those who were admitted Wednesday were injured in Tuesday's attack on a base in Mosul, though Shaw said most were.

The attack killed 22, including 14 U.S. service members, four U.S. civilians, three Iraqi National Guard members, and one "unidentified non-U.S. person," the U.S. military command in Baghdad said Wednesday evening.

Of the 69 wounded, 44 are members of the U.S. military, seven are U.S. contractors, five are civilian workers for the Defense Department, two are Iraqi civilians, 10 are contractors of other nationalities, and one is of unknown nationality and occupation, the military said.

Seventeen of those arriving at Landstuhl on Wednesday were in critical condition in the intensive care unit, Shaw said.

Initial reports said a 122 mm rocket ripped through the tent's ceiling but the U.S. Defense Department said later it was most likely a suicide bomber, partially because the shrapnel in the explosion included small ball bearings, which are often used in such attacks.

Shaw said she did not know if Landstuhl's doctors had been able to determine whether the shrapnel wounds they had been treating had been caused by such projectiles.

Landstuhl was expecting at least another 30 casualties on Thursday, though it was again not immediately clear whether they were injured in the Mosul attack.