A man fell into the water as he was exiting his boat at a marina in Inver Grove Heights and drowned, authorities said Thursday.

The incident occurred well after dark Wednesday at Twin City Marina on the Mississippi River shoreline, said Dakota County Sheriff Tim Leslie.

Sheriff's deputies and fire personnel got the man out of the water and began resuscitation efforts before he was taken to Regions Hospital in St. Paul, Leslie said.

The man later was declared dead, Leslie said. His identity has yet to be released.

Emergency medical personnel on the scene reported that the man, in his 50s, had been underwater for about 1 ½ hours, according to dispatch audio.

The sheriff said investigators continue to look into why the man fell.