South Korea on Tuesday offered its condolences to the North over the recent collapse of an apartment building in Pyongyang, which is presumed to have resulted in heavy casualties.

The accident occurred on May 13 in the Pyongchon district, where the construction of the 23-story building was nearing completion, prompting People’s Security Minister Choe Pu-il and other senior executives to offer a rare public apology.

The extent of the damage remains unknown but the death toll is expected to be high as 92 households had already moved in, Seoul officials said.

“We convey our deepest condolences over the loss of many lives in the accident,” the message reads. It was delivered in the morning via a telephone link based in the border village of Panmunjeom under the name of Red Cross president Yoo Jung-keun, the Unification Ministry said.

The consolation dispatch, the first since 2006, marks an unusual cordial gesture between the two sides. It followed a recent heated war of words over the communist country’s preparations for a third nuclear test, U.S. President Barack Obama’s visit to Seoul and a South Korea-U.S. summit, and the discovery here of spy drones believed to have flown in from the North.

Pyongyang also sent a similar message to the South in the wake of the ferry disaster last month that left more than 300 people dead or missing.

In 2004, Seoul offered not only condolences but also food, medical supplies and other relief support after an explosion at the Ryongchon train station in the northwestern province of North Pyongan, which is estimated to have killed at least 150 people, injured 1,300 and damaged around 8,100 housing units.

Officials said the ministry is not considering providing any support yet.

“The message was sent by the Red Cross from a humanitarian standpoint, so it would be going too far to think beyond that,” a ministry official told reporters on condition of anonymity.

“North Korea has not requested any support from international organizations and I think the priority should be on figuring out the exact magnitude of the damage.”

By Shin Hyon-hee (heeshin@heraldcorp.com)