At least six people have been killed and dozens of others injured in a series of strong earthquakes in Japan on Monday that triggered tsunami warnings and evacuation orders.

According to the Japan Meteorological Agency(JMA), aftershocks continued into Tuesday morning after a magnitude five-point-seven earthquake struck the Noto Peninsula at 4:06 p.m. Monday, followed by the strongest tremor at 4:10 p.m. with a magnitude of seven-point-six.

The agency said that the major quake occurred at a very shallow depth, with the epicenter located 30 kilometers east-northeast of Wajima City in Ishikawa Prefecture.

According to Japan’s public broadcaster NHK, aftershocks continued into the morning in Ishikawa and nearby prefectures after the strongest quake on Monday evening, with a four-point-nine-magnitude tremor reportedly hitting the region at 4:42 a.m. Tuesday.

The JMA said that the seven-point-six-magnitude quake was followed by 93 tremors in the region up to midnight, and led to tsunami warnings for Honshu and Hokkaido and other regions that were later downgraded.