Oil prices plummeted on Friday, after the U.K.’s vote to leave the European Union in a nationwide referendum triggered a selloff across markets, according to the Wall Street Journal.

Nearly 52% of the U.K. electorate voted in favor of leaving the EU.

Trading was volatile on Friday, with oil falling by around 6% earlier in the session. Brent was down by around 5.5% by the European mid-session at $48.12 a barrel. Its U.S. counterpart, West Texas Intermediate, was down 5.1% at $47.54 a barrel.