Hall of Fame pitcher Pedro Martinez said on social media that several of his family members were inside the nightclub that collapsed in the Dominican Republic early Tuesday.
"I still have family members that are still in the rubbles, and we don't know what happened to them," Martinez said in a video posted to Instagram on Tuesday night.
At least 221 people were killed, with hundreds more injured from the collapse at the Jet Set nightclub in Santo Domingo that occurred around 1 a.m. Tuesday.
Former World Series champion Octavio Dotel and former MLB player Tony Blanco were among the dead, as was Nelsy Cruz, the governor of the Monte Cristi province in the country and sister of seven-time MLB All-Star Nelson Cruz.
Dotel reportedly was alive when rescue crews located him and at least seven others, but authorities said Tuesday night that Dotel was declared dead upon arrival at a local hospital after his condition worsened.
Dozens of people clad in black and white streamed into a funeral home Wednesday to pay their respects to Dotel.
"This has been devastating for our country," former sports minister Danilo Díaz told TV station CDN. "He was always positive, a collaborator, a friend."
Boston Red Sox great David Ortiz told reporters that the number of people who attended Dotel's wake spoke volumes.
"He was a person whom everyone loved. It's very hard, very hard, truly," said Ortiz, who recalled how he spoke with Dotel almost every day. "He was very funny. Octavio was a guy who was a fighter."
Martinez, a three-time Cy Young Award winner and an eight-time All-Star, grew up in a suburb of Santo Domingo. He is a baseball analyst.
"It is with a heavy heart that it is my turn to actually send condolences to all our family members and the people here in the United States who have family over there," he said in the video. "We're all sad. We're all affected by the tragedy. ... Our hearts are with you. We all are affected."
Before speaking about his new deal ahead of Toronto's game at Boston on Wednesday, Vladimir Guerrero Jr. said his thoughts were with his native Dominican Republic.
"I want to send my condolences for those families that lost a loved one in that tragedy. ... That my heart, my soul is with my entire country right now," he said.
The government announced late Wednesday that it was moving into a recovery phase after rescue crews searched for survivors for more than 24 hours following the collapse. Officials said earlier that they had rescued 145 people from the wreckage of the nightclub.
An in-depth investigation into the collapse is expected. Authorities have not released any preliminary findings or commented on what might have caused the roof to fall.
The Associated Press, Reuters and Field Level Media contributed to this report.