He said the last official figures for Papua New Guinea's autonomous region of Bougainville were 40 cases of the coronavrius - a rise from just three last Thursday.
Toroama said Bougainville's health officials had been trying to convince people to wear masks, wash their hands and maintain social distance.
There had been criticism of Bougainvilleans failing to respond to the Covid-19 surge but Toroama said Buka town would now go into a full, 14-day, lock down.
Bougainville had managed to largely evade Covid-19 until the recent escalation in numbers across Papua New Guinea caused surge in the region.
Bougainville had wanted to avoid Covid-19 because of its poor health infrastructure, though some temporary facilities have been provided by aid donors.
Toroama said the police would be on standby to ensure that people follow the lockdown rules.
Photo supplied Caption: Aerial view of Buka