Japan’s NHK TV says an explosion occurred at a reactor at the Fukushima Number One nuclear power plant on Tuesday.

A spokesman for the Nuclear and Industrial Safety Agency told the public broadcaster that the latest explosion occurred at 6:10 a.m. Tuesday at the power plant’s number-two reactor.

The report said that an emergency countermeasures team ordered the evacuation of employees from the plant, as loud crashing sounds were heard near the reactor container where fuel rods are stored.

The reactor container plays the crucial role of blocking radioactive materials from leaking out in the event an accident occurs.

According to NHK, as of 7:50 a.m. Tuesday, the radiation level at the Fukushima plant stood at one-thousand-941 microsievert per hour. Japan allows an hourly exposure of 500 microsievert.