TOKYO -- A Japanese police officer died in an apparent suicide after being found shot in a restroom at the prime minister's office in central Tokyo early Friday, investigators said.

The 25-year-old man of the Tokyo Metropolitan Police Department (MPD)'s riot squad was found bleeding from the head in a toilet inside the west gate guard station at the prime minister's office and was taken to hospital but was soon confirmed dead, according to the MPD.

A gun was found on the floor near the body and a bullet had been fired from the gun. No suicide note was found, the MPD said.

Investigators said the officer, identified as Yuta Kurokawa, appeared to have taken his own life with the gun he was carrying.

Prime Minister Fumio Kishida, who has been on a weeklong tour in Africa and Singapore, was not in the office at the time, local media reported.