Firemen were called to rescue dozens of people trapped in lifts yesterday after homes and offices in Mongkok and Yau Ma Tei were hit by a power cut. Police were called to direct traffic when lights stopped working due to the power failure at 4.15pm. The Hospital Authority said a back-up system came into operation at Queen Elizabeth and Kwong Wah Hospitals. Movie-goers were evacuated from the Broadway Cinematheque in Yau Ma Tei, and candles were lit in some restaurants, but MTR services were unaffected as they use a separate power supply. A government spokeswoman said there were 38 reported incidents of people trapped in lifts in Yau Ma Tei and Mongkok between 4.15pm and 5.05pm, but no casualties were reported. A spokeswoman for CLP Power said the blackout was caused by an unspecified problem in a Yau Ma Tei substation. She said power was restored to 98 per cent of affected users at 4.40pm and fully restored at 5.04am.