London police sealed off an area around Kings Cross station on Tuesday after smoke was seen coming from a double-decker bus.
Police sent a bomb squad and later reported that a small engine fire was probably to blame. No explosives were found.
“It’s a fire,” a police spokesman said. “We put cordons in as a precaution. It’s been looked at and it’s only a fire.”
The incident tied up traffic around Kings Cross, which was the scene of one of the four bombings on July 7 that killed 52 people.