ASTORIA, Queens (PIX11) — The NYPD on Friday identified a suspect accused of stabbing an FDNY EMS worker over 20 times in Queens on Thursday.

Investigators alleged 34-year-old Peter Zisopoulos went on a vicious, unprovoked attack, stabbing EMT Lt. Alison Russo-Elling, 61, two dozen times after she stepped out of her station house near 20th Avenue and 41st Street around 2:20 p.m. Zisopoulos was then chased by witnesses into his apartment, where he barricaded himself inside, police said.

NYPD negotiators were able to get him to surrender, and he was taken into custody. Zisopoulos was charged with murder and criminal possession of a weapon, according to authorities.

Members of the FDNY mourned Russo-Elling’s death on Thursday. Acting FDNY Commissioner Laura Kavanagh said Russo-Elling served the department for nearly 25 years.

“She was absolutely beloved on this job,” Kavanagh said. “Members of EMS serve only to help and save other people’s lives. To be attacked and killed in the course of helping others is both heartbreaking and enraging for our department in ways I cannot describe.”

Russo-Elling served as a first responder during the Sept. 11 terror attacks, according to officials. She is the 1,158th member of the FDNY to die in the line of duty and the second member of EMS to die in the line of duty in the last five years.