Performers and theatre goers watching a matinee performance of Woyzeck, starring Star Wars actor John Boyega, were asked to leave the historic theatre in Waterloo after a suspect package was reportedly found somewhere in the building.
Several audience members have been tweeting pictures and video of the drama unfolding, as police cordoned off the area and directed and began searching the building.
Twitter user @Lazulus, who was apparently watching the show, tweeted: "Old Vic has been evacuated, police everywhere. No idea what's going on."
They added that the audience, cast and crew had all assembled in the gardens of the Imperial War Museum.
Shops, resturants and pubs have also been cleared as police closed off the area around The Cut.
The Old Vic theatre has been evacuated after a suspicious package was found
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Star Wars actor Boyega was reportedly onstage when staff wearing hi-vis jackets entered the auditorium 10 minutes into the performance and asked everyone to leave.
Several audience members tweeted praise for theatre staff for their calm and professional attitude during the evacuation.
A Met Police spokeswoman said police were called just before 2.40pm to reports of a "security alert".
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"The theatre took the decision to evacuate the building," the spokeswoman said.
"Road closures have been put in place. Specialist officers are on scene.”
More to follow.