US Homeland Security is the third government agency to be hacked by Russia

The U.S. Department of Homeland Security was named as the third agency to be attacked by the Russian intelligence hackers, Reuters reported Monday.

According to the Washington Post, the list of those impacted is expected to grow larger as the week goes along.

"The fact that the department charged with safeguarding the country from physical and cyber attack was victimized underscores the campaign’s significance and calls into question the adequacy of federal cybersecurity efforts," reported the Post.

While there were breaches of cyber-security software company FireEye, another company, SolarWinds was also hacked, and it's believed that it's how Russians were able to get in, said FireEye's John Hultquist.

“SolarWinds was clearly a door that they could walk through,” he said. “We’re shutting this door. But they’re still in these organizations. There are a lot of information security teams right now who are probably going to be working on this problem through Christmas.”

Rep. Adam Schiff (D-CA) warned that it also will impact hundreds of American companies.

Read the full report at the Washington Post.