Gas leak

Not only that but she seemed offended by my leering

You seem like a particularly nasty bit of work today.
I would of just expected the driver to check their mirror and not swerve when there is a cyclist on their inside, and that that act of moving out the way of an ambulance almost caused a collision, which may of needed another ambulance.

Panic on the streets of London...
Maybe that was the idea behind closing the road.
Just a wild guess...