Police were relieved, though, when it turned out all of the materials were fake.

“After we examined the luggage, which appeared to contain 10 objects similar to detonators, they turned out to be dummies and not harmful at all,” National Police spokesman Insp. Gen. Anton Bachrul Alam said.

The luggage belonged to three South Korean citizens — two men and a woman — who arrived in Jakarta on Sunday night on a Korean Airlines flight from Incheon, South Korea, according to Salahudin Rafi, spokesman for airport operator Angkasa Pura II.

They were set to board a Lion Air flight to Balikpapan, East Kalimantan, but security officials pulled them aside and searched their luggage after scanners turned up images of objects that were similar to detonators, chemicals and jumper cables.

“The materials were packed in a special bag and they were made by a Korean company, Global Hanwha Explosives Dream,” Rafi said.

According to the Web site of the Hanwha Group, the company has a manufacturing unit that produces industrial explosives, munitions and machinery.

The three Koreans were detained but eventually released.

“They were going use them in a presentation to a coal company in Balikpapan, Multi Mikrotama Kimia,” Anton said.

However, Rafi said the three South Koreans were unable to prove their story during the questioning. “They claimed to have come at the invitation of the company, but when our officers asked for proof, they could not show documents to back up their explanation,” he said.

Multi Nitrotama Kimia could not be reached for confirmation, but according to its Web site, it supplies ammonium nitrate, an essential ingredient for explosive materials, and provides explosive services to various mining companies.

Anton said police would summon the coal company officials to testify that the materials were for demonstration purposes only.

“We haven’t named anyone as suspects here, but we want to know for sure,” he said.

Rafi also said that regardless of the fact that the materials turned out to be fake, the incident showed that airport security officers were alert and followed safety protocols to avoid a potentially disastrous incident.

“This is proof that our officers are careful. We’re still in high alert,” he said.