Vice President Joe Biden went farther than President Obama in describing the downing of a Malaysian passenger jet over Ukraine on Thursday afternoon, saying it “apparently” was shot down.

“I say 'apparently' because we don't actually have all the details. I want to be sure of what I say. Apparently, have been shot down. Shot down, not an accident. Blown out of the sky,” Biden said during remarks at a Netroots Nation conference in Detroit.

Biden said a team of U.S. officials are on their way to the crash site in Ukraine to “see if we can get to the bottom of this.”

A Ukrainian government official earlier Thursday said its military was not responsible and claimed that pro-Russian separatists shot down the jet. Pro-Russian separatists also are denying responsibility for the downed plane.

Reacting to reports that 23 U.S. citizens were onboard, Biden said: “Obviously, that's our first concern. And we're now working every minute to try to confirm those reports as I speak.”

The Kiev Post is reporting that Ukrainian intelligence officials have obtained recordings of intercepted calls between separatists and Russian military officers, in which the militants take responsibility for shooting down the airliner.

Obama earlier in the day addressed the crash in opening remarks during a speech in Delaware, saying it “looks like this might be a terrible tragedy.”

The president also pledged to try to determine whether there were any Americans on board.

“That is our first priority,” he said.

“I've directed our national security team to stay in close contact with the Ukrainian government. The United States will offer any assistance we can to help determine what happened and why, and as a country, our thoughts and prayers are with all the countries and passengers — wherever they call home,” Obama added.

Sen. John McCain, R-Ariz., speaking to NBC earlier Thursday, said “there's going to be hell to pay” if the crash was the result of a rocket attack by pro-Russian separatists.