Commuters were left panicked on Monday night when builders accidentally drilled down into a London Underground tunnel, causing debris to fall on passing trains.
The Central Line was part suspended at 5.30pm for three hours last night between Marble Arch and Shepherd’s Bush.
The contractors were thought to be working on an extension to the Westfield shopping centre in White City.
People on the carriages said that the trains were hit by falling rocks and debris.
Lawrence Kenny, 27, told the Evening Standard: “It was really loud. Everyone was in complete shock.
“People were looking around in disbelief. Some people clearly thought we were under attack or there might have been a bomb.
“Some people came rushing into our carriage from the one in front trying to get away. We must have been showered with the debris for 30 seconds or so.”
Kenny said that some of the rocks were “the size of rugby balls”.
TFL said that the work being carried out was nothing to do with them, but external contractors.
A spokesman also said that no damage was caused to the train or track.
Peter McNaught, Operations Director, said: "The Central line was part suspended yesterday evening due to an obstruction on the track in the Shepherd's Bush area, caused by external contractors involved in building work in the local area.
"Our engineers worked hard to clear the debris as quickly as possible and ensure the line was safe to reopen to passengers.
"We will be carrying out a full investigation into the cause of this issue alongside those involved."