SEATTLE — An explosion from a firecracker inside a moving Jeep blew off the driver’s hand early Saturday and scattered debris over half a block, prompting initial fears over the man’s intent, police and neighbors said.

Witnesses saw a flash of light from inside the vehicle, a red Jeep with a gray top, as it drove down a residential street in north Spokane, police said.

Donald Wilkes, 61, said the blast rattled his house and woke up everyone inside. He initially thought someone had crashed into his parked truck, and when he ran outside he found the street filled with smoke and the Jeep stopped just against his 6-foot-tall cedar fence.

“I looked around for something that got hit, but there was nothing,” Wilkes said. “My son reached in to pull the keys out of the ignition and make sure he didn’t go anywhere, and that’s when we saw his hand was missing. It blew it right off at his wrist — they found part of it half a block away.”

Wilkes’ son, 30-year-old Nicholas, and another neighbor applied a tourniquet to the man’s left arm. The man was stocky, estimated at about 28 to 30 years old, and coherent. But he wouldn’t answer questions about what he had been doing, Wilkes said.