Two FBI agents have been killed in a training accident in Virginia, officials said Sunday.
The accident, which occurred Friday, involved members of the FBI's elite Hostage Rescue Team, AP reported.
The victims were identified as Christopher Lorek, 41, and Stephen Shaw, 40.
No details on how it happened were disclosed, but an FBI spokeswoman in the Norfolk area said the deaths did not involve gunfire, the Washington Post reported.
Other media reports said it involved a helicopter but officials would not elaborate on the circumstances surrounding the tragedy.
Officials said Lorek, who joined the FBI in 1996, is survived by his wife and two daughters, aged 11 and 8.
Shaw had been in the FBI for eight years and is survived by his wife, and two young children.
FBI director Robert Mueller paid tribute to the men, describing them as "brave and courageous", Fox News reported.
"Like all who serve on the Hostage Rescue Team, they accept the highest risk each and every day, when training and on operational missions, to keep our nation safe," he said in a statement.
"Our hearts are with their wives, children, and other loved ones who feel their loss most deeply. And they will always be part of the FBI Family."