Police are investigating two explosions at Seoul Station and Gangnam Express Bus Terminal about 30 minutes apart on Thursday.

There have been no reports of injuries yet from the two blasts, officials said.

The explosions caused chaos with citizens hurriedly leaving the two public transportation hubs. Police have not ruled out the possibility of terrorism, officials said.

The blast at the bus terminal in southern Seoul occurred around 11:55 a.m. What is presumed to have been a can of butane gas exploded in a locker in the waiting room at the terminal, police said.

“There was the sound of an explosion. Smoke and flames were seen coming out of the locker. People were trying to put out the blaze with fire extinguishers. After opening the door, there was a can of butane gas connected to an electrical wire,” one of the shop keepers in the area told reporters.

Another blast at Seoul Station in central Seoul occurred at around 11:22 a.m. Police arrived at the site after they were informed that there was smoke billowing from a locker in the waiting room at the station. They found a burned backpack and what is presumed to be a can of butane gas, officials said.

After analyzing the closed-circuit TV footage from Seoul Station, police found that at around 5:51 a.m., a man wearing a hat put a bag in the locker where the fire broke out, officials said.

Police have cordoned off the areas at the two sites and mobilized its Explosive Ordnance Disposal unit to find out if there are any incendiary devices planted there

Police suspect that the explosives were planted by the same person as they occurred at nearly the same time. They are trying to find if it is a case of premeditated terrorism and if there are any accomplices.

Following the explosions, police have ordered its units across the country to inspect all lockers and storage facilities at bus terminals, subway stations and other public transportation sites.

Meanwhile, a renowned U.S. nuclear expert said that South Korea should not rule out the possibility that it could become a target of international terrorists.

At a meeting of South Korean and U.S. nuclear experts in Seoul, Matthew Bunn, professor of public policy at Harvard University, made the remark after reporters asked him about the possibility of terrorist attacks on South Korea following the recent death of al-Qaida leader Osama bin Laden.

He added that the impact of possible terrorist attacks could be international, particularly affecting world trade.

By Song Sang-ho (sshluck@heraldcorp.com)