SEOUL - Wailing air raid sirens and cellphone alerts calling for rare evacuations rattled residents of the South Korean capital Seoul early on Wednesday after North Korea launched what it said was a satellite.

North Korea launched the rocket towards the south, South Korea’s military said, prompting emergency alerts and evacuation warnings in parts of South Korea and Japan.

“I was so panicked, 911 lines were busy and the Internet was slow,” said Ms Lee Ju-yeon, 33, a resident in the densely populated city of 9.6 million who has a nine-month-old child. “So without knowing what was really happening, I was about to head down to a basement wearing a wrap carrier with my baby.”

The sirens started in Seoul at 6.32am (5.32am, Singapore time) as the city issued a “Presidential Alert” asking citizens to prepare for potential evacuation.

Then came a second mobile alert minutes later calling for an actual evacuation, which remained in place for at least 10 minutes until the city authorities said it was a false alarm sent in error.

Ms Lee did not evacuate after seeing a television headline saying it was a North Korean space vehicle flying farther south, but she showed photographs of friends packing bags, readying to leave.

While residents of Seoul are used to living in the shadow of threats from their nuclear-armed neighbour, an element of complacency has crept in among many in the city about the risks and how to respond.

The two countries are still technically at war seven decades after the Korean War ended in an armistice.

Some office workers in the central district said they had considered during their commute how to respond to the alarm, such as by withdrawing cash or hoarding water.

“I understand it was a mistake, but even if it has to be simple, that alert message should have said what went on and where to go,” said Mr Kim Jong-hyun, 48, who was on his way to work after dropping off his child at school.

Later on Wednesday, Seoul Mayor Oh Se-hoon apologised for confusion over the city’s alert but defended the decision to send one as a precaution for public safety. He said the city would improve the wording in future messages and on warning systems.

“Alerts” and “evacuation” were trending topics on Twitter in South Korea on Wednesday morning, with confused tweets scrambling to grasp what was going on or to find evacuation areas.

“Hey guys, given Twitter is still working, I guess it is not a war,” one user with the handle @Kimisnim__ said. REUTERS