Moscow, Ramadan 18, 1435, July 15, 2014, SPA -- At least five people were killed and more than 100 injured Tuesday in Moscow when a packed underground train derailed, authorities said, according to dpa. Georgy Golukhov, the head of Moscow's health department, said 106 people were hospitalized and more than half of them were in critical condition, Russian news agencies reported. The accident happened when the train suddenly braked in a tunnel during the morning rush hour. Investigators said the reason was a wrong signal. "The signal was shown erroneously because of a voltage drop," said Valdimir Markin, the spokesman for Russia's Investigative Committee. Rescue workers were trying to free passengers from one car that remained stuck in the tunnel. --SPA 12:49 LOCAL TIME 09:49 GMT www.spa.gov.sa/w