The South Korean media are questioning whether authorities could have anticipated that more than 100,000 people would gather in Seoul's Itaewon district for Halloween.

At least 154 people, many of them youths, died on Saturday night in a massive crowd surge in the popular entertainment district. Two Japanese women are among the victims.

A woman in her 50s living near the scene said she is heartbroken, and that she hopes similar incidents never happen again.

A memorial incense stand was set up in the city center on Monday. President Yoon Suk-yeol and his wife came to offer flowers and to observe a moment of silence.

The local media say that more than 100,000 people used a railway station closest to the scene of the incident on the day.

They quoted an expert who analyzed footage of the scene as saying that there were more than 10 people per square meter.

They also quoted eyewitnesses as saying that some people lost consciousness while still standing.

The media point out that investigators are expected to look into whether sufficient security measures had been taken.