Radioactive materials seeped out of a nuclear power plant in Japan following explosions at two of the reactors on Tuesday as government authorities there attempt to avoid a nuclear catastrophe following last week’s record earthquake.

Japanese Prime Minister Naoto Kan said Tuesday that radiation levels had increased significantly in areas around the reactors, warning people within a 30-kilometer radius of the Fukushima Daiichi nuclear plant to stay indoors to avoid exposure.

The plant in Fukushima Prefecture is about 240 kilometers away from Tokyo.

Kyodo News Agency says radiation levels Tuesday morning just south of Fukushima were almost 100 times the normal level.

According to weather forecasts, wind will blow southwest from Fukushima toward Tokyo on Tuesday evening before shifting direction to the sea.

A spokesman for the Nuclear and Industrial Safety Agency told NHK that the first explosion was at the power plant’s number-two reactor.

The report said 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.