BLANTYRE/DAR ES SALAAM (Reuters) - A four-year-old boy and two adults were killed and up to 250 people injured on Sunday when a 6.0 magnitude earthquake destroyed buildings in Malawi's northern district of Karonga.

A local government official called on thousands of people to leave their homes because of damage to buildings and the threat of further tremors.

Another tremor struck neighbouring Tanzania, according to the U.S. Geological Survey (USGS), but initial reports said there was no serious damage or injuries.

The Malawi quake, which occurred at 0119 a.m. (2319 GMT Saturday) at a depth of 9.4 miles (15.2 km), was the latest in a series in the uranium-rich Karonga district this month. A one-year-old child was killed on December 8.

"Two people have died, a four-year-old child and his grandmother, after the house they were sleeping in collapsed on them," police spokesman Enock Livasoni told Reuters.

Another man died in hospital as a result of head injuries, said nurse who declined to be identified.

She said up to 250 people appeared to have been injured, but no other patients were in critical condition.

Livasoni said damage to villages was extensive, with many schools and government buildings affected.