The lead singer of the Boston rock band Morphine, Mark Sandman, died of a heart attack suffered onstage during a concert outside Rome, Italy, on Saturday night, according to an Associated Press report.

The 46-year-old singer and bass player for the trio, known for their mostly guitarless beat-noir sound, collapsed onstage in front of several thousand spectators at a music festival just before midnight, AP reported.

"We're devastated," band manager Deborah Klein was quoted as saying Sunday. "We don't even know what to say. We're all in shock."

Morphine, who caught fire with their second release, Cure for Pain, had recently finished a live album, due in October. The band had nearly completed work on another project, Klein told AP.

Sandman died on the second day of a three-day music festival at the Giardini del Principe in Palestrina, 30 miles east of Rome. Festival promoter Flavio Maniri said Sunday's performances would be dedicated to Sandman, according to the AP report.

Despite a doctor's attempts to save the singer at the scene, he was pronounced dead in an ambulance en route to a nearby hospital, AP reported. Sandman was not known to have health problems, Klein is quoted as saying.

Known for his deep, murky baritone, Sandman wrote all the songs for Morphine, a guitarless group that also includes saxophonist Dana Colley and drummer Billy Conway. Sandman's lyrics expressed desperation, confusion and world-weary inevitability, rounding out Morphine's dark edge.

A high-school dropout who grew up in a Boston suburb, Sandman drove a cab in Boston, worked around the country and even traveled on a fishing boat, before hitting it big as a musician. After the demise of his earlier band, Treat Her Right, Sandman started experimenting with different instruments.

In an interview with Addicted To Noise, he said he developed the concept of a guitarless Morphine after he began listening to one-stringed African instruments while living in Cambridge. This gave him the idea to string his bass differently to experiment with the variations in sound.

The group, which started out playing around Boston and Cambridge in the early 1990s, released five albums: Good, Cure for Pain, Yes, Like Swimming (RealAudio excerpt of title track) and B-Side. Having gained the support of college radio, Morphine built their following and contributed music to soundtracks for the films "Get Shorty," "Beautiful Girls" and "Postcards From America," as well as to the television series "Homicide: Life on the Street."

Among their songs are "Good," "You Speak My Language," "Do Not Go Quietly Unto Your Grave" and "The Only One," spare compositions that helped establish the band's reputation for dark hard-rock.

Funeral arrangements for Sandman, who is survived by his parents, were reportedly pending.