The captives held in a Moscow theater knew they were in danger, but they probably didn’t expect to die at the hands of their rescuers.

The tragic “rescue” early Saturday of hostages in a Moscow theater should cause government around the world to reassess their development and use of chemical agents as weapons.

After a 58-hour standoff with the Russian military, Chechen rebels who had taken control of the filled theater set a deadline of sunup Saturday. If their demands were not met by then, they would begin killing hostages.

Rather than wait for the rebels to make good on their pledge, Russian special forces pumped a secret gas into the theater. The gas had the intended effect of incapacitating the rebels. In fact, the 50 captors all were killed by the effort. Unfortunately, the gas also resulted in the deaths of many of the hostages. As of Tuesday, 118 hostages had died as a result of the incident 116 from the effects of the gas.

There is no doubt that the hostages were in grave danger. A number of the rebels had explosives strapped to their waists and rigged around the theater. Taking some offensive action probably was a valid decision by Russian officials, but the use of the gas raises serious questions.

First, it was obvious that the Russians didn’t really know what effect the gas would have. An aide to President Vladimir Putin sought to justify the risk afterward by saying, “There was not one scenario that could have guaranteed the lives of the hostages and the special forces in a theater filled with 330 pounds of explosive devices.” That may be true, but using a gas whose effects aren’t known isn’t exactly a calculated risk. In hindsight, it appears that several other options, possibly including a conventional assault, might have resulted in fewer hostage deaths.

To compound the problem, after the catastrophic impact of the gas became obvious, Russian forces refused to divulge the nature of the gas to medical personnel who were treating the victims. U.S. officials now say the gas was a fast-acting opiate. It’s unclear whether identifying the gas earlier might have saved lives.

The situation in the Moscow theater, indeed, was a difficult one. Almost any strategy probably would have resulted in at least some hostage deaths. Nonetheless, the fact that more than 100 hostages died as a direct result of a chemical agent pumped into the theater by the forces attempting to rescue them does offer cause for reflection.

The use of chemical agents in military actions is likely to become more widespread. Hopefully, officials in Russia and elsewhere will use this episode as a lesson in how to use or refrain from using chemical agents, especially when their effects haven’t been thoroughly researched.