Donald Trump postponed his official vice president announcement after a truck plowed into a crowd celebrating Bastille Day in Nice, France on Thursday.

@realDonaldTrump: In light of the horrible attack in Nice, France, I have postponed tomorrow's news conference concerning my Vice Presidential announcement.

An attacker killed about 60 people and injured 100 when he drove a truck at high speed into crowds watching Bastille Day fireworks in the French Riviera city of Nice late on Thursday, local media quoted officials as saying.

@realDonaldTrump: Another horrific attack, this time in Nice, France. Many dead and injured. When will we learn? It is only getting worse.

The New York businessman's campaign previously said he would make the announcement on Friday.

@realDonaldTrump: I will be making the announcement of my Vice Presidential pick on Friday at 11am in Manhattan. Details to follow.

Earlier on Thursday, NBC News reported that Trump has picked Indiana Gov. Mike Pence as his running mate.