Police in Brooklyn are investigating after they said a woman riding her bike was hit and killed by a tractor trailer Monday morning, the 18th cyclist killed by a vehicle on New York City streets this year.

• De Blasio Plan Calls for Building 30 Miles of Protected Bike Lanes a Year

"It is terrible, it is really shocking, and scary too," cyclist Michael Tully said. "I mean, these are places I bike all the time, so that is obviously upsetting to hear."

Em Samolewicz, a 30-year-old artist and yoga teacher, was riding along Third Avenue near 36th Street, blocks away from her Sunset Park home.

Just before 9 a.m., Samolewicz swerved into traffic to avoid hitting a van door. That's when she was hit by a 10-wheel tractor trailer, police said.

The driver of the van spoke to NY1 shortly after the accident. But he did not want to appear on camera.

"I think she lost [her] life, I think she died, which made me very sad," he said. "I ride bike around before and this same accident happened to me, but it wasn't this fatal. A guy opened his back door — passenger opened his back door — and I hit it, and I fell down, but that time it was much, much easier than what happened today."

Police said the driver of the truck that hit Samolewicz initially didn't know what happened, stopping a few blocks from the scene after someone flagged him down. Police had not charged him by Monday evening.

"The city is wild and people don't look, people don't follow the rules, and I feel like everyone is guilty of that," cyclist Joe McMan said. "But it is a tragedy that is terrible."

Third Avenue has six lanes for cars and not a single designated bike lane. Samolewicz died just eight blocks from where the first cyclist was killed in 2019. She is the 12th cyclist fatality in Brooklyn.

"I wouldn't feel comfortable going from Bed-Stuy to here," cyclist Anastasiya Muravyeva said. "It just doesn't seem that bike-friendly."

Cycling advocates are calling on the city to take "swift action" to include a Third Avenue redesign as a part of its new "Green Wave" plan that in part calls to building more protected bike lanes in New York City each year.

In a statement, the city transportation department said, "We are working hard on the protected bike lane on nearby 4th Avenue, completing a very large section between 1st and 38th Streets this year, which will be completed by late Fall. In addition to the east-west connections we created in 2018, we will look at ways to improve 3rd Avenue for those who choose to walk and bike along the corridor."