Less than 24 hours before an attack carried out at the United Kingdom’s Houses of Parliament in Westminster on Wednesday, a thread on 4Chan may have announced the attack, according to a report from Gizmodo.

The thread, posted in the popular imageboard site’s politically incorrect (otherwise known as /pol/) community, appeared at around 3 p.m. London time Tuesday and contained a cryptic message posted in Morse code.

When translated from its dots and dashes form, the code read, “goto http://pastebin.com/zluxdmza.” The Pastebin link contains another code, this time in binary that translates to GPS coordinates near Big Ben. Reports indicate the attacker that carried out the assault on Westminster crashed his vehicle near this location Wednesday.

Read: Gunshots, Injuries Reported In Westminster In Apparent Terrorist Attack

The Pastebin link was created by a guest account, meaning it could not have been edited after it was posted.

The original post, which has been archived but is still viewable, also contains an image included by the original poster that shows two guns and a hastily computer-edited note that reads ““/pol/ 21-3-2017.” The image of the guns appears to have been taken from a 2010 forum post on a luxury car message board.

4chan users have been in a panic about the coded messages in the wake of the attack, which has left at least four people dead and at least 20 people injured, over fears the post will lead to the site being shut down.

According to Gizmodo, 4chan’s current owner and operator Hiroyuki Nishimura said he is aware of the situation and is “ready to respond for law enforcement agency.”

Read: 4chan Falsely Takes Credit For Information In Intelligence Dossier On Trump

An armed police officer and the man believed to be the attacker are among the four reported dead from the attack in Westminster. Reports indicate the attacker hit several pedestrians with his vehicle while driving on the Westminster Bridge before crashing near Big Ben and attempting to enter Parliament.

The attack is being treated as an act of terrorism, according to British officials.