SUNSET PARK, Brooklyn (WABC) -- An investigation is underway after a bicyclist was struck and killed by a tractor trailer in the Sunset Park section of Brooklyn.It happened shortly after 8:30 a.m. Monday near the intersection of 36th Street and 3rd Avenue, underneath the Gowanus Expressway.A 30-year-old woman was riding her bike north on 3rd Avenue when she hit or swerved to avoid the door of a van as it was opening.The 46-year-old driver of that van, who asked that we not identify him, spoke with Eyewitness News.He said he had just returned from the repair shop, jumped into the van, closed the door and re-adjusted the driver's seat. He suddenly realized he needed to get out again to adjust the passenger side seat.So he reopened the driver's side door, just as the bicyclist was passing. The bicyclist was thrown into the tractor trailer's path.Police arrived to find the woman lying in the road. She was rushed to Lutheran Medical Center, where she was pronounced dead. She was later identified as Em Samolewicz.The van driver said he was in shock when he realized what had happened.Police say the 37-year-old driver of the tractor trailer stopped a few blocks away.So far no charges have been filed against anyone involved.----------