Fourteen people have died in bombing at the St. Petersburg metro on Monday, April 3, Russian health minister Veronika Skvortsova said Tuesday, revising the previous toll of 11 deaths, Sputnik reports.

"Today it can be said that 14 people died. Eleven died at the scene and three died in an agonizing condition from fatal injuries," Skvortsova said via video link-up.

On Monday, an explosion occurred in the St. Petersburg underground on the stretch of rail between the Sennaya Ploshchad and Tekhnologichesky Institut metro stations at around 3 p.m. local time (12:00 GMT). At least 51 people were injured, according to Russia's St. Petersburg Chief Administration of Ministry of Emergency Situations.

Russia's Investigative Committee has opened a criminal investigation into a suspected terrorist attack.