A blast at a pharmaceutical laboratory in South Africa injured at least 35 people, police said on Monday. Fire erupted after the explosion in the eastern province of Mpumalanga caused fire, badly damaging a part of the building, police said. The flames were eventually extinguished by the fire fighters and the injured were rushed to hospital for treatment. Rescuers are still at the scene trying to find survivors possibly trapped in the debris of the ruined building, according to police. While it was unclear what caused the explosion of the laboratory, some people said it was an act of arson. Authorities have thrown a probe into the blast.