Attorney General Eric Holder told a Senate panel today that the Justice Department is not prepared to work with Congress to probe the fatal Nov. 5 shootings at Fort Hood, Texas,  until federal law enforcement authorities have a better understanding of the crimes allegedly perpetrated by Maj. Nidal Hasan.

The FBI and the military are in the early stages of investigating the shootings at the Army base near Killeen, Texas. Holder, speaking at a wide-ranging Senate Judiciary Committee oversight hearing for the Justice Department, said federal authorities are still trying to sort out all of the facts in the case.

“Once we have a handle on that, we can work with the committee to propose ways to prevent a tragedy like this from happening again,” Holder said.

There are few reported details on what caused Hasan, an Army psychiatrist, allegedly to kill 13 people at the military base. But federal authorities have been investigating e-mail conversations between Hasan and Anwar al-Awalki, a radical Muslim cleric in Yemen. Holder said at the hearing that the e-mails are “disturbing.”

Members of Congress have pushed for immediate hearings on the massacre. Senate Homeland Security Committee Chairman Joe Lieberman (I-Conn.) will hold a hearing tomorrow on the shootings, but no Obama administration officials are slated to testify.

Aides from the Justice and Defense departments have briefed senior members of Congress in closed door meetings, according to The Washington Post. Lieberman is also slated to meet with Holder and Defense Secretary Robert Gates this afternoon, according to Politico.

The Obama administration has made it clear to lawmakers that it doesn’t want Congress interfering with its probe of the shootings at this time, according to The Post.

“I want a successful prosecution, but I also want to know what happened,” Senate Judiciary Committee Chairman Patrick Leahy (D-Vt.) said at today’s hearing.