Leo's postmortem of the victims reveals there were two guns used, and possibly a second shooter.
| Name | Type | Role | |
|---|---|---|---|
| Dudi Appleton | Writer | ||
| Jim Keeble | Writer | ||
| Jason Bailey | Guest Star | Tactical Command Officer | |
| Robert Bertrand | Guest Star | Jason Renfrew | |
| Anna Chancellor | Guest Star | Chief Supt Karen Somerville | |
| Elliott Tittensor | Guest Star | Scott Weston | |
| Paul Kynman | Guest Star | Chief Inspector Layton Kant | |
| Matt Bannister | Guest Star | Graduate Student 2 | |
| Joe Marsh | Guest Star | Matt Frisk | |
| Annabelle Dowler | Guest Star | Paramedic 2 | |
| Jessica Clark | Guest Star | Graduate Student | |
| Malcolm Scates | Guest Star | Dominic Weston | |
| Tom Bennett | Guest Star | DC Andy Saich | |
| Daniel Caltagirone | Guest Star | Peter Snelling | |
| Juliet Oldfield | Guest Star | Claire Bolt | |
| Connie Walker | Guest Star | Pamela Weston | |
| Michael Tulloch | Guest Star | CO19 Officer | |
| Phyllis Logan | Guest Star | Jennifer Mears | |
| Toby Wharton | Guest Star | Neil Corrigan | |
| Mark Gillis | Guest Star | DCI Graham Gibson | |
| Neil Madden | Guest Star | Paramedic 1 | |
| Farren Blackburn | Director |