SINGAPORE – A 100kg World War II bomb found in Upper Bukit Timah was successfully detonated on Tuesday afternoon, after more than 4,000 nearby residents were evacuated in the morning.

The police said in an update on Facebook that the bomb was successfully disposed of by the Singapore Armed Forces (SAF) Explosive Ordnance Disposal team at 1.45pm.

In an updated Facebook post at about 5.10pm, it said the Building and Construction Authority (BCA), national water agency PUB, grid operator SP Group and HDB had completed their assessment of the construction site where the bomb was found.

Nearby drains and pipelines, and evacuated buildings and roads, were found to be structurally safe, and residents had been informed they could return home.

The bomb relic was unearthed during excavation works last Wednesday at the construction site for The Myst condominium.

What followed was the largest evacuation exercise involving the disposal of a World War II-era bomb, affecting some 1,000 residential units at The Linear, Hazel Park, Hazel Park Terrace and Block 154 Gangsa Road.

The detonation operation involved more than 40 SAF personnel, the army said in a Facebook post. It said soldiers used sandbags and concrete blocks to build a protective wall around the bomb to minimise the impact from the blast.

The bomb, believed to be one of the largest wartime munitions unearthed in Singapore, was destroyed in two controlled explosions.

A blast from the first detonation was heard from Block 153 Gangsa Road at around 12.30pm. The blast from the second detonation was heard from Senja-Cashew Community Club (CC), about 2km away.

Mr John Chia, a 65-year-old passer-by, heard the first explosion from a nearby Shell petrol kiosk. “I was standing opposite the Shell petrol kiosk station along Upper Bukit Timah Road. It was a very loud blast, it shocked me,” he said.

As a precaution, train services on the Downtown Line were suspended during the detonation operation, the Land Transport Authority (LTA) said in a Facebook post on Tuesday. 

In another Facebook post at around 5.30pm, LTA said affected roads in the area had re-opened, and bus and train services had resumed normal operations.

Police officers had put up roadblocks at affected streets at around 10.30am, to the surprise of some commuters. 

Private tutors Annabelle Leow, 26, and Goh Zhi Wei, 39, learnt of the bus diversions from a notice pasted on the windscreen of an affected bus, service 67, that they were on. The pair then changed their lunch plans. 

The authorities had told residents on Sunday they should not be home between 8am and 7pm on Tuesday. Before vacating their homes, residents were told by police to mark their doors with a green strip of paper.

One of the designated areas for them to go to was the Senja-Cashew CC.

When The Straits Times arrived there on Tuesday morning, about 100 residents were seen milling about, most of them elderly.

Ms Cheah Yoke Peng, 77, a resident of Hazel Park, went to the CC from Changi Airport with her luggage in tow after her flight from China landed at about 7am.

She had spent seven days in Xi’an with her brother and sister, and was exhausted after the five-hour flight.

Ms Cheah said the exercise was an inconvenience. “I had no rest at all. I am so sleepy now,” she said.

Tourist Roman Ansay, 38, on the other hand, said he was happy to be a part of history. The Filipino national was in Singapore to visit his brother, a resident of Hazel Park.

Foreign Minister Vivian Balakrishnan, the MP for the ward in Holland-Bukit Timah GRC where the bomb was found, visited Senja-Cashew CC on Tuesday morning and spoke to some residents.

Dr Balakrishnan said he wanted to thank the agencies involved, including the police, the SAF, the BCA and the Housing Board.

He said the evacuation of residents went smoothly as they left their homes on time and cooperated with the police. He had been worried about traffic jams, but it was managed effectively by the police.

He said: “At the community level, you can see we have actually over-prepared, because we were not sure exactly how many people would need additional help. But we thought it was better to over-prepare than under-prepare.”

He noted that as it was a work day, most people had gone to work, while students were at school and proceeding with their lives, as they should.

Dr Balakrishnan said the authorities were focused on the vulnerable, and had to make arrangements for the bedridden to have access to daycare.

He said there were facilities in Bukit Panjang, and wheelchair users were tended to at the CC.

He was very pleased at how the community supported one another.

“I am happy with the way the community has responded, the calmness and composure of our people and, of course, the professionalism of our agencies. So, a big thank you to everyone,” he said.

He added: “Singapore is a well-organised, calm, composed place where when things happen, we are able to respond effectively. And because there’s that trust and cooperation and that sense of looking out for each other, it makes things so much easier.

“It’s another aspect of that strong Singapore spirit. So, a lot to be thankful for.”

People’s Association grassroots leader Linda Ng had earlier said Senja-Cashew CC would be able to hold 1,500 residents.

A special programme had been put in place for the day at the CC, and to stave off boredom for waiting residents, there were video screenings in the morning and an arts and craft class in the afternoon, where they learnt to fold pipe cleaners into flowers.

A study room with Wi-Fi was set up for children.

Among the displaced were 25 dogs from dog daycare and boarding centre Rock n Ruff. Its president, Mr Derrick Tan, said the canine evacuation began at 6.45am. The dogs were ferried to the CC with trunks of food, feeding bowls, play pens and carriers.

Mr Tan said: “The process was relatively smooth, even though we had to make a few 20-minute trips to and fro to transport all the animals.”

The bomb disposal operation also disrupted lessons at Greenridge Secondary School, which had switched to home-based learning for the day.

SMRT bus services 67, 176, 178, 961, 970, 979 and 983 were affected on Tuesday between 11am and 7pm. They skipped several bus stops in the closed-off Upper Bukit Timah Road area. Four other bus services operated by SBS Transit and Tower Transit Singapore were also affected.

In 2016, another 100kg bomb relic was found and disposed of at a Mandai construction site. There were no civilian evacuations then.

In 2019, 600 residential units were evacuated when a 50kg World War II bomb was found and later detonated near the former site of popular nightclub Zouk.

In 2021, a bomb relic was found at a temple construction site in Geylang, prompting the evacuation of 100 people.

Another bomb was found in 2020 at a corner terrace unit in Bishan, but only 12 households were affected.

• Additional reporting by Sarah Koh, Vihanya Rakshika and Ang Qing