A catastrophic roof collapse at a nightclub in the Dominican Republic's capital left at least 79 people dead on Tuesday and emergency crews were working frantically after nightfall to pull survivors from the rubble.

About 155 people were injured.

Families of the victims gathered near the Jet Set nightclub seeking information about their loved ones.

"I still have family members that are still in the rubble, and we don't know what happened to them," Pedro Martinez, a 17-season Major League Baseball player, said in a video shared on his Instagram account in the evening.

The deceased included a popular singer, a provincial governor, and former Major League Baseball pitcher Octavio Dotel, authorities said.

Juan Manuel Mendez, head of the Dominican Republic's emergency operations center, said earlier on Tuesday that the exact number of people inside the club at the time of the collapse remained unclear.

The emergency crews' capacity was increased as "more heavy equipment has been used to speed up the removal of debris and continue the search efforts," presidential spokesperson Homero Figueroa said in a statement.

The disaster struck during a concert by popular Dominican merengue singer Rubby Perez, who was among those killed, according to his manager and family members near the site. The event was attended by politicians, athletes and other prominent figures.

Also among the victims was Nelsy Cruz, the governor of the northern Monte Cristi province, President Luis Abinader said. Cruz was the sister of former baseball player Nelson Cruz, a seven-time MLB All-Star.

Former MLB players Octavio Dotel and Tony Blanco also died in the collapse, local authorities confirmed. Dotel died en route to a local hospital after being pulled from the debris, a spokesman for the nation's sports ministry said.

Dotel, 51, debuted for the New York Mets in 1999 and played until 2013 for more than a dozen teams.

"Thinking about our people in the Dominican Republic," Carlos Mendoza, manager of the Mets, said at a press conference.

Relatives were receiving psychological support and the cause of the roof collapse remained under investigation, officials said.