First was 4P 1A 7P 2E. (4E was elsewhere.) Second was 1P EN1 2BRONTO 23AL. 2P decided they had to go because the Bronto was on the job. (When the Bronto first was in the fleet, very few pumpers could supply the oomph needed to supply it, and 2 Pump was one of them. Also the staff on 2 Pump are trained for operating the Bronto.)
Second alarm can be called at any time by the incident command, or, in rare cases, at the discretion of dispatch if the incident seems bad enough (VERY rarely used).