Cruz hit a motorcycle with his vehicle early Monday morning, killing all three riders. Police told Dominican newspaper Diario Libre that Cruz was driving under the influence of alcohol.
The accident also took place after curfew, which is in effect in the Dominican Republic due to COVID-19, according to Biertempfel.
Cruz's agent, Rafa Nieves, told Biertempfel his client is "fine" and uninjured. Nieves didn't comment on the charges.
Cruz has a court hearing Wednesday, though he's yet to be charged with any crime. If he's charged and found guilty, he could face up to five years in prison.
The Pirates are aware of Cruz's involvement in a "tragic accident," according to a team statement obtained by Jason Mackey of the Pittsburgh Post-Gazette.
The 21-year-old shortstop is the third-ranked prospect in the Pirates organization after posting an .832 OPS with 34 RBIs and 11 steals in the minors last season.
Pittsburgh acquired Cruz from the Los Angeles Dodgers in a 2017 trade involving Tony Watson.