Rescuers raced to find survivors on Tuesday among the rubble of a Dominican Republic nightclub where at least 98 people, including a Major League Baseball star, were killed when the roof collapsed.

Renowned Dominican merengue singer Rubby Perez, who was on stage at the popular Jet Set nightclub when the roof caved in shortly after midnight, was one of those caught up in the calamity.

Emergency workers said the 69-year-old was among dozens of people trapped in the rubble, some of whom were heard crying for help.

Several Dominican media outlets later reported that Perez had been found dead but Juan Manuel Mendez, director of the Emergency Operations Centre, said forensics experts had "not confirmed that they found the body."

Over 370 rescue personnel combed mounds of fallen bricks, steel bars and tin sheets for survivors.

Among the dead was 51-year-old retired MLB pitcher Octavio Dotel, who won a World Series in 2011 with the St Louis Cardinals.

He was rescued alive but died of his injuries while being taken to hospital, local media reported.

Local media said there were between 500 and 1,000 people in the club when disaster struck shortly at 12:44 am local time. The club has capacity for 700 people seated and about 1,000 people standing.

Dozens of ambulances ferried the injured to hospital, as scores of people gathered outside the venue desperately seeking news of their loved ones.

Perez was on stage when there was a blackout and the roof came crashing down, according to eyewitness reports.

Also among the dead was the governor of the Monte Cristi municipality, Nelsy Cruz, according to President Luis Abinader.

The death toll started at 15 and kept rising throughout the day. By evening it had reached 66.

President Abinader visited the scene and declared three days of national mourning. (AFP)