The National Weather Service has declared Boston is at risk of being struck by tornadoes on Wednesday evening as extreme weather in the western part of Massachusetts has hit Springfield with two twisters which have killed at least 4 people.

A tornado watch is in effect in the Boston area until 11 p.m. EDT Wednesday evening, with showers and thunderstorms expected.

Massachusetts' Gov. Deval Patrick declared a state of emergency Wednesday evening and called for 1,000 members of theNational Guard to help with cleanup.

Patrick said one person was killed in Springfield, two in Westfield and one in Brimfield about 20 miles east.

The region is under threat of large hail and damaging wind as well. Some thunderstorms may produce heavy rain that could produce localized flooding, the NWS said.

There was a confirmed touchdown by the National Weather Service in the western city of Westfield and just west in Springfield.

Boston police are trying to keep people out of open spaces, a police spokesperson told the West Roxbury Patch.

The twisters in Massachusetts follow extreme weather in various parts of the MidWest in recent weeks, which has killed hundreds of people in one of the deadliest storm seasons.

READ: Tornadoes Strike Massachusetts, 4 Dead