An employee for Schindler Japan, the domestic subsidiary of the Switzerland-based elevator manufacturing and maintenance company, had deliberately stopped elevators in five apartment buildings in and around Tokyo, trapping users inside, the transport ministry said Wednesday.

The 36-year-old male employee, who was fired by Schindler Japan as of Aug. 5, has admitted his involvement, saying he wanted to harass his employer because he was in trouble with the firm.

According to the ministry, the employee joined the company in 2008. Between June 28 and Aug. 1, he entered the buildings of the government-funded UR apartments in Tokyo and Chiba prefectures to stop the elevators there. Using a key given only to maintenance companies, he activated safety measures on seven occasions and stopped the elevators for as long as 45 minutes at a time.

A total of seven residents were trapped, including a woman who felt sick inside an elevator and was taken to a hospital. There were no injuries.

Schindler Japan said the man might have held a grudge against the company because he was demoted from a branch manager to a rank-and-file employee in June.

The cases surfaced after the employee himself was trapped inside an elevator at a "love" hotel in Ibaraki Prefecture on Aug. 2. When he called the hotel to report the incident, he didn't push an emergency button but instead got out by himself. Schindler Japan had found it suspicious and started investigating.

Schindler Japan has apologized for the incidents. UR is considering filing a criminal complaint against the man.