A 25-year-old multipara was hospitalized at the first period of labor with moderately strong contractions. This is her third pregnancy. She has a history of one cesarean section due to clinically narrow pelvis and one artificial abortion. Suddenly she developed severe abdominal pain and weakness. The blood pressure dropped to 90/50 mm Hg. Moderate bloody discharge appeared from the vagina. The fetal heartbeat cannot be auscultated. The labor activity has ceased. Make the right diagnosis: