A 17-year-old girl was stabbed to death outside a Bronx apartment building in broad daylight Thursday, cops said.

The teen was knifed in the chest on Boynton Avenue near Watson Avenue in the Soundview neighborhood around 2:15 p.m., authorities said. 

She was taken to Jacobi Medical Center, where she was pronounced dead, police said. 

Three people who ran into the building after the bloodshed were taken into custody in connection to the stabbing, cops and sources said.

One of the three, another teenage girl, is suspected of launching the fatal attack, police sources said.

No one had been charged by later in the afternoon. 

The circumstances leading up to the deadly violence were under investigation.