The U.S. Federal Emergency Management Agency is trying to refine its weather alert system so that cellphone users not at risk do not get scared.

In Philadelphia, a "severe alert -- flash flood warning" message Wednesday went to many people far from the nearest creek likely to rise, The Philadelphia Inquirer reported. While the few people likely to be at risk undoubtedly appreciated the message, others did not.

Many newer mobile devices include the feature, which became active in April. FEMA officials say it provides warnings at times when many people may not be keeping an eye on the television news.

The Joplin, Mo., tornado last year hit on a Sunday afternoon, while a recent violent windstorm that devastated parts of the Mid-Atlantic region arrived late at night on a weekend.

Damon Penn, a FEMA official, said the agency is working on narrowcasting the warnings. But he said the agency does not want to make it too narrow because some people may be driving into danger.

"This is all about saving lives," he said.