The FBI issued a recent warning to state election officials to beef up their cybersecurity measures after foreign hackers broke into one state’s election system and targeted another.

The FBI confirmed to Fox News on Monday it issued a “flash” alert on Aug. 18, urging states to contact their Board of Elections if they suspect a breach.

In the flash alert from its cyber division, the FBI said it was investigating a pair of incidents and giving states specific signs to look out for to determine if their system had been hacked.

The FBI did not say which state was hacked or which one was targeted but says eight computers were involved.