The former editor-in-chief of prominent Hong Kong newspaper Ming Pao — whose ouster in January sparked protests by many of the paper's staffers — was stabbed Wednesday morning and has been hospitalized in critical condition, police said.

The incident prompted an outcry from local journalist groups, with one lumping it in with other threats against journalists in the city in recent months. Meanwhile, Hong Kong's chief executive, Leung Chun-ying, said he was gravely concerned about the assault.

Current Ming Pao chief editor Cheung Kin-bor said in an interview that Kevin Lau was in the hospital after being attacked on the street by a knife-wielding assailant on Tai Hong St. in the city's Sai Wan Ho neighborhood.

"We still know nothing about the details," said Mr. Cheung. "We are awaiting reports from the doctor and the police."

Police said that they received a call around 10:20 a.m. from a 49-year-old victim, surnamed Lau. According to Mr. Lau, the police said, his assailant was wearing a helmet and attacked him with a knife before jumping onto a motorcycle driven by another driver and speeding away.