WASHINGTON — Four U.S. Secret Service agents were injured in a head-on collision in New Hampshire that killed the driver of the other vehicle, the Secret Service and New Hampshire police said on Wednesday.

The driver of the other car crossed into an oncoming lane Tuesday night and hit the vehicle carrying the agents who were on duty, the local police department said in a statement. Two other people were injured.

It was not immediately known why the agents were in New Hampshire, but leading Democratic presidential candidate Hillary Clinton, who has a Secret Service detail because of her status as former first lady, was campaigning there on Tuesday night.

Secret Service Director Joseph Clancy said in a statement that Secret Service personnel suffered injuries that were serious but not life-threatening.

Two passengers in a Mercury Sable that hit the agents’ Ford Taurus were hospitalized and the driver, 45-year-old Bruce Danforth, was killed, said police in Wakefield, New Hampshire, where the accident occurred.

Danforth did not have a valid driver’s license and had “an extensive criminal history,” the Wakefield Police Department said in a statement, adding that it would take some time for results from his autopsy and blood tests.

The Wakefield Police Department said it was working with New Hampshire State Police on the accident investigation.

Wakefield is about 100 miles north of Boston and near New Hampshire’s border with Maine.

Storms and harsh winter weather hit New Hampshire on Tuesday, forcing Republican presidential candidate Jeb Bush to cancel a campaign event.

New Hampshire will hold one of the first primary elections in the run-up to the November 2016 presidential election, making it a popular place for candidates to campaign at this time of year.