Rudolph W. Giuliani was expected to make a full recovery after a vehicle slammed into his car on Saturday, leaving him with a fractured vertebra and other injuries.

Mr. Giuliani, the former New York mayor and lawyer for President Trump, was riding in a Ford Bronco that was rear-ended in New Hampshire on Saturday evening. The police said the injuries suffered by Mr. Giuliani, 81, and the two drivers involved in the accident were not life-threatening.

The police said the crash was under investigation and that no charges had been filed. Initial reports of how it unfolded, based on accounts from Mr. Giuliani’s head of security and the New Hampshire State Police, were a little unclear.

Here’s what we know.

What happened?

Mr. Giuliani was riding in a Ford Bronco when a Honda HR-V hit his vehicle on a northbound section of Interstate 93 in New Hampshire, the state police said in a statement. The two vehicles hit a median and were heavily damaged, the police said.

The driver of the Honda was a 19-year-old from Concord, N.H., according to the police. The Bronco was being driven by an adviser to Mr. Giuliani, Theodore Goodman.

That much is clear. The moments leading up to the crash are not.

Michael Ragusa, Mr. Guiliani’s head of security, said that the Bronco had been flagged down by a woman who was the victim of domestic violence. The former mayor called 911, waited for help to arrive, and then left, Mr. Ragusa said.