Two people were listed in serious condition Sunday evening after a car crashed into a tree in Topsfield, police said.

The crash happened around 5 p.m. on Ipswich Road near Willowdale Road, according to Detective Brendan Gahagan. The man driving the car and a woman passenger were both taken to Beverly Hospital, officials said. The woman was later transported by helicopter to a hospital in Boston.

The cause of the crash is still unknown, though it may have been the result of a medical condition, officials said. Police are investigating the crash.

Abigail Feldman can be reached at abigail.feldman@globe.com.