NEW : At least 50 students killed , 100 injured ; toll is expected to rise . Red Cross official says dozens of students appear to be trapped in Haiti school . Rescue workers digging through rubble near Port-au-Prince , official says . Comment:
NEW : At least 50 students killed , 100 injured ; toll is expected to rise . Red Cross official says dozens of students appear to be trapped in Haiti school . Rescue workers digging through rubble near Port-au-Prince , official says . School could have as many as 700 people in it , rescue official says .