A spokesperson for the Cardenales de Lara, Valbuena and Castillo's team in Venezuela, confirmed to Fletcher the two had died, and the team's official Twitter account announced the news early Friday morning.
According to Fletcher, Valbuena and Castillo played in a Venezuelan league game Thursday night. At some point after the game, they were both passengers in a car driven by teammate Carlos Rivero when the car hit a rock and veered off the road.
"This is a very sad day for our sport as we mourn the deaths of Luis Valbuena and Jose Castillo," MLB Commissioner Rob Manfred said in a statement on Friday, per MLB.com. "It is clear by all the stories today that they loved baseball and made an impact on their teammates and the clubs they represented. On behalf of Major League Baseball, I extend my deepest condolences to their families, friends and fans, particularly those in their native Venezuela."
Valbuena played in the majors from 2008 to 2018, most recently appearing in 96 games for the Los Angeles Angels last season before the team released him in August. His best year came in 2016 when he batted .260 and slugged .459 while hitting 13 home runs and collecting 40 RBI for the Houston Astros.
Castillo debuted in MLB in 2004 and played four seasons for the Pittsburgh Pirates. He then split the 2008 campaign with the San Francisco Giants and Astros.