When an American tank forced its way onto the grounds the Kunduz trauma hospital in Afghanistan destroyed in an airstrike earlier this month on Thursday, The Guardian reports, it may have destroyed evidence of potential war crimes.

In a statement after Thursday’s “intrusion,” MSF said that they were told that the tank had been carrying investigators from the U.S.-NATO-Afghan coalition: “Their unannounced and forced entry damaged property, destroyed potential evidence and caused stress and fear.”

Ten patients and 12 staff members of Médécins sans Frontières (MSF), or Doctors without Borders, were killed in the October 3rd attack. According to an Associated Press report earlier on Thursday, U.S. intelligence analysts knew that the target of the attack was a hospital.

Meanwhile, the International Humanitarian Fact Finding Committee (IHFFC), an independent humanitarian commission created under the Geneva Conventions in 1991, is waiting for confirmation from the United States and Afghan governments that they will cooperate with an independent investigation.

“The commission has already offered its services to the governments of the USA and Afghanistan,” a Swiss foreign ministry spokesman told Reuters in an email on Wednesday. “Any investigation would require the agreement of both governments, however.”

“We have received apologies and condolences, but this is not enough. We are still in the dark about why a well-known hospital full of patients and medical staff was repeatedly bombarded for more than an hour,” Dr. Joanne Liu, MSF’s International President, said. “We need to understand what happened and why.”

Reuters reports that a White House spokesman said that Obama—who apologized to MSF last week—assured Liu that a U.S. investigation would “provide a transparent, thorough and objective accounting” of the attack.

Photo credit: AP Images. Contact the author of this post: brendan.oconnor@gawker.com.