The FBI has arrested a Northern Virginia man for threatening to put pipe bombs on Metro trains.
In an affidavit filed in federal court, the FBI says Awais Younis, an Arlington County resident, was plotting to blow up Metro trains during rush hour.
The FBI says Younis, who goes by a number of different aliases, told an acquaintance via Facebook how to build a pipe bomb, and talked about placing bombs on trains and underneath a sewer head in Georgetown.
The FBI also says Younis posted photos of himself on Facebook in which he is shown with explosives and an AK-47 rifle.
The FBI says it became aware of Younis' plans late last month after his acquaintance forwarded a copy of their online chat to federal agents.
Younis is the second Northern Virginia man this year to be arrested for plotting to carry out a terrorist attack on the Metro.