AMHERST - Severe weather and the possibility of tornadoes prompted the first real-time activation of an emergency alert system that sounded sirens and played prerecorded messages on the University of Massachusetts campus Sunday.

For those who were outside, including a large number of elementary-school age children playing soccer on fields adjacent to Boyden Gymnasium and Alumni Stadium, and their parent and sibling spectators, the system gave them clear instructions to find shelter until the dangerous weather passed.

UMass spokesman Ed Blaguszewski said Thursday that the decision to activate the outdoor warning system was made by emergency management director Brian Olsen and Deputy Police Chief Patrick Archbald because of a developing weather situation.

"For much of the day, there was a severe weather watch regarding tornadoes and severe thunderstorms," Blaguszewski said.

The $225,000 system, installed last summer, includes sirens in eight locations. The system, which can broadcast warnings across the campus, using both tone and voice alerts, is one of a number of tools the university uses. Depending on the situation, such as weather emergencies, hazardous material spills and active threats, the methods of communication can be email, updates of the website, text messages and an emergency phone line.

The use of the outdoor alert system Sunday, after several practice runs, may have startled some residents in Amherst, as the sound apparently traveled a good distance.

Shirley Nelson, of Webster Court, located in the Echo Hill section of Amherst more than two miles from campus, sent an email to the Gazette that she could hear the sirens accompanied by a muffled voice. She called it "an unnerving perplexity."

"We have lived here for six years and have never heard that there is such a warning system at UMass, and this time we learned it only by the grapevine," Nelson wrote.

The alert system was also a topic of conversation at this week's Select Board meeting.

Diana Stein, who lives on Red Gate Lane, said she was surprised she could hear the sirens at her home and wanted more information about the system.

For Alisa Brewer, who lives on Fairfield Street, the sirens were not a surprise. She signed up for text messages from the university and was already aware of the regular testing of the outdoor alert system that took place last fall and this spring.

Blaguszewksi said it is unclear how far sound from the system travels. The sirens and prerecorded messages, which can also be used as a live public address system, are designed to carry throughout the entire 1,463-acre main campus.

"The nature of these systems is you can't control how far it will project," Blaguszewksi said. "It will vary depending on weather conditions and physical characteristics of landscape and buildings."

The university is still getting anecdotal information of where people heard the sirens, which will help improve the system. There are still some kinks to work out, he said, including whether the "all clear" signal and message needs to be repeated so people understand an emergency has ended.

But Blaguszewski said he doesn't think it is necessarily a bad thing if the system's sounds travel off campus, pointing out that Amherst Police and Fire departments and Hadley emergency dispatch were notified.

"The point is to serve the public, enhance public safety, and as we use it more often we'll learn from these instances," Blaguszewski said.

More information about the alert system, installed by Acoustic Technology Inc. of Boston is available at www.umass.edu/alerts/outdoorwarning.php.