Vance Boelter is accused of shooting Hortman and husband Mark at their home on June 14 and is also suspected of shooting and injuring Senator John Hoffman and his wife Yvettte.

Boelter was apprehended by police in a field in Minneapolis on Sunday night local time, the Associated Press reports.

The 57-year-old is alleged to have killed former House Speaker Hortman and her husband at her home before fleeing the residence on foot.

Hoffman and his wife, Yvette, were injured at their Champlin home, about 15 kilometres away.

Boelter was arrested in a rural area in Sibley County, south-west of Minneapolis.

“Where he was ultimately taken into custody was in a field,” Drew Evans, superintendent of Bureau of Criminal Apprehension, said.

He said authorities believe Boelter acted alone.

A criminal complaint unsealed on Sunday night says Boelter, 57, faces two counts of second-degree murder and two counts of attempted second-degree murder in the deaths of the Hortmans and the wounding of Hoffman and his wife.

The FBI had issued a reward of up to $US50,000 ($77,000) for information leading to his arrest and conviction.

They circulated a photo taken Saturday of Boelter wearing a tan cowboy hat and asked the public to report sightings.

Authorities allege Boelter wore a police uniform at the time of the shooting.

Evans said authorities found a car very early on Sunday (local time) they believed Boelter was using, a few kilometres from his home in Green Isle, in the farm country about an hour west of Minneapolis.

He also said they found evidence in the car that was relevant to the investigation, but did not provide details.

– Reported with Associated Press