MOSCOW — Two suicide bombers, possibly women, set off explosions in separate subway stations in central Moscow during the morning rush hour Monday, killing at least 37 people and injuring more than 60 others in what officials said was the deadliest and most sophisticated terrorist attack in the Russian capital in six years.

Russian President Dmitry Medvedev ordered his government to provide full aid to the victims and their families and to tighten security at airports and railways. “We must consider this problem on a national scale,” he said. “Obviously, we have not done enough.”