The Associated Press is warning its reporters to stay vigilant after several received harassing messages from Bernie Sanders supporters.

Danny Spriggs, the AP’s vice president for global security, said some reporters have received angry emails, social media messages and phone calls after the AP declared Hillary Clinton the presumptive Democratic presidential nominee.

“We have not received any specific security threats,” Spriggs said in an email to employees, according to Poynter. “It is always good to practice situational awareness around AP bureaus and offices.”

The AP on Monday declared Clinton the Democratic nominee, saying she had enough pledged delegates and superdelegate support to reach the party’s threshold for the nomination.