(CNN) -- Major League Baseball is to investigate a possible racially motivated incident involving Baltimore Orioles centerfield Adam Jones during their game at San Francisco Giants Sunday.
Jones took to Twitter to claim that a fan threw a banana at him during the ninth inning at AT&T Park.
Jones, who is an African-American, voiced his displeasure on his official account.
"I want to thank whatever slap---- threw that banana towards my direction in the last inning," he posted. "Way to show (your) class (you) jack---"
MLB Senior Vice President of Public Relations Patrick Courtney told CNN Sports Monday: "We are looking into this situation."
San Francisco also promised action, but in a statement released to CNN said they had to date been unable to identify the person responsible.
"The Giants have a zero tolerance policy against this type of behavior, which results in immediate ejection from the ballpark," it read.
"We would like to extend our sincerest apologies to Adam and the entire Orioles organization for this unfortunate incident.
"The inappropriate actions of this individual in no way reflect the values of our organization and our fans."
The Orioles enjoyed a 10-2 victory over last season's World Series winners, rallying from an early two-run deficit to score 10 unanswered runs.
Jones hit a three-run homer at the top of the ninth inning to help clinch the victory.
He said the reaction of some on Twitter to his angry posting could mean him closing his account.
"Good chance this means I get off social media soon," he later tweeted.