Updates to Team Fortress 2 have been released. The updates will be applied automatically when your Steam client is restarted. The major changes include:

Team Fortress 2
Fixed a sentry gun exploit that let Engineers build multiple sentries
Fixed Engineers being able to build level 3 mini-sentries using The Wrangler
Fixed the Holy Mackerel hit triggering the first blood event in Arena mode
Fixed seeing error particle systems in old demos
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