The police in Massachusetts said Friday that they were investigating a kidnapping case that started last weekend with a routine traffic stop and has led to the discovery of three bodies in a house.

At about 11:15 p.m. on Sunday in Springfield, a city in western Massachusetts, the police tried to pull over a man driving a vehicle without a taillight, Ryan Walsh, a Springfield Police Department spokesman, said on Friday. The driver took off and officers in two cruisers chased him for about 10 minutes until they blocked him. He stopped, backing into one of the cruisers, Mr. Walsh said.

Officers discovered an injured woman in the vehicle, and she told the police she had been held captive by the man, identified as Stewart Weldon, 40, for about a month, Mr. Walsh said.

“Thank you guys for saving my life,” the woman told officers, according to the police report. “I didn’t think I was ever going to get away.”