US tornadoes kill four

Massachusetts Governor Deval Patrick declared a state of emergency and authorised 1,000 National Guard troops to be called up to provide support after at least two tornadoes touched down.

"It is early going yet, so those are not final numbers, although we are hoping and praying and working as hard as possible to keep the fatalities limited to those four," Patrick told a news conference.

Tornadoes are rare but not unheard of in the northeastern United States.

Southeastern states, especially Alabama, were hit hard in April and Joplin, Missouri, was devastated by a massive tornado in May that killed 134 people.

In Massachusetts, the first tornado touched down at about 4.30pm local time in Springfield, the third largest city in the state, said Chris Vaccaro, a spokesman for the National Weather Service.

Heavy winds churned the Connecticut River and the area was pounded by hail and driving rain.

A second tornado hit Springfield, 90 miles west of Boston, at about 6.20pm, authorities said. State police said at least 33 people were injured in Springfield.

Damage included "trees and numerous power lines down, roofs ripped off of homes, things like cars and SUVs that have been toppled over," said Scott MacLeod, a spokesman for the Massachusetts Emergency Management Agency.

The severe weather was the result of colder air clashing with a warm, humid system that has produced some record temperatures for early June through much of the mid-Atlantic states, meteorologists said.