It is not safe for residents to return to their homes now.

The Singapore army specialists on Tuesday successfully detonated a 100-kilogram World War II-era bomb discovered at a construction site. More than 4,000 people were evacuated from nearby residences for the controlled detonation, reported news agency AFP. Notably, the unexploded aerial bomb was found in Singapore’s northeastern suburb of Bukit Timah where a condominium was being built.

In a video posted on Facebook by the Singapore Army, military officers were seen setting up sandbags around the area where it would be detonated to contain the blast. The bomb was then detonated at a construction site, with a loud boom. The two blasts took place at about 12.30 pm and 1.45 pm, the latter of which could be heard from about two kilometers away from the site. Police had warned residents not to be alarmed by the loud explosion and to avoid the area.

”An Unexploded Ordnance (UXO) was recently discovered at a construction site along Upper Bukit Timah Road. The SAF Explosive Ordnance Disposal (EOD) team from the 36th Battalion, Singapore Combat Engineers (36 SCE) was activated and identified the UXO to be a 100kg World War II aerial bomb. The UXO was assessed to be unsafe to be moved to another location and was successfully disposed of on-site earlier this afternoon.

Involving more than 40 SAF personnel, the disposal was done in a controlled manner. Protective works involving the use of sandbags and concrete blocks were also put in place to minimise the impact from the blast,” the Facebook post reads.

Watch the video here:

The detonation of the unexploded aerial bomb has been described as the largest-ever exercise involving a WWII relic in Singapore, as per Reuters. After the detonation, buildings and roads were deemed structurally safe and residents were allowed to return home, police said.

According to local media reports, the device likely contained around 47 kilograms of explosives which would have been strong enough to blow up the surrounding apartment block.

There have been a few discoveries of unexploded devices in Singapore in recent years. As per a PTI report, a 50 kg aerial bomb was found at Jiak Kim Street in the River Valley suburb area during excavation works at a construction site. In 2016, the Singapore Armed Forces’ Explosive Ordnance Disposal unit also disposed of a 100 kg war relic found at a construction site in Mandai.