David Cameron is to spend Friday with police in Cumbria, where shootings left 12 people dead and 11 injured.
The PM sympathised with communities left "deeply torn" by Wednesday's "horrific events" but warned against knee-jerk changes to gun laws.
Police investigations are continuing into what caused Derrick Bird, 52, to go on the rampage, amid reports of a possible family row over a will.
The taxi driver was pursued by armed police before turning a gun on himself.
Cumbria Police recovered a shotgun and .22 rifle with telescopic sight and have since confirmed that Bird was licensed to hold both weapons. He is believed to have done so for 20 years.
