Mechanical’s steel defenses have confined its people; another barrier is being welded across the stairs during the retreat.
The original barricade sealed Mechanical’s security entrance from floor to ceiling and wall to wall. A narrow gap beneath the turnstile admitted only one person at a time, leaving those waiting outside exposed to gunfire from above.
Peter Billings later reported that the attackers had time to prepare an assault from their side of the wall. As defenders retreat, another set of steel plates is being welded across the narrow staircase passage.
Steel plates close the original security entrance, leaving a narrow opening under the turnstile. Another set of plates is being welded across a narrow stair passage.
Steel barriers intended to hold back attackers during Mechanical’s defense and retreat.