Vientiane, Laos —
Rescue teams in Laos said they were investigating a possible “knock reaction” deep inside a network of flooded caves where two men are believed to remain trapped.
Although the phenomenon could indicate possible signs of life, rescue workers stress that further investigation is needed before they can be sure whether the knocks were caused by the stranded men.
The sound was heard as rescuers rappelled down a newly discovered vertical shaft that could allow safer entry into the flooded cave and lead to a room where the men might be.
“We cannot yet confirm whether the knocking sound came from a trapped victim, but we can confirm that there was a clear knocking sound in response to the signal,” Thai professional cave diver Kenkard Bongkawon told CNN by phone on Monday.
Rescue workers have now heard at least two knocks in the past 24 hours.
Manat Artmongkrong, a Thai rescue engineer, posted on Facebook that he could hear the reaction 70 meters (230 feet) down the shaft.
“Reactions could be heard from only 5 meters away. This is good news. Will update soon,” he wrote.
