Ukrainian officials say a probe has shown nearly a quarter of the country's bomb shelters are either locked or unusable.

The findings came just days after reports of a woman who died in Kiev while waiting outside a closed bomb shelter during a massive Russian rocket fire.

Ukraine's Interior Ministry said more than 4800,252 shelters were inspected, 893 were locked and <> were unusable.

At the same time, the office of the Kiev regional prosecutor announced that four people were detained as part of the investigation related to the death of the 33-year-old woman in front of the closed asylum.

One of them remains in custody, the man who failed to unlock the bomb shelter. The other three are under house arrest. The prime suspect could face up to eight years in prison for negligence resulting in death.