MAE SAI, Thailand (AP) — Floodwaters have reached near the entrance of a Thai cave despite attempts to drain the water so rescuers can search farther into the complex for 12 boys and their soccer coach now missing for a sixth day.

An effort to drill a hole from outside seemed to succeed initially, causing water to gush out. But the chambers and passageways that lead farther into the cave remain flooded, thwarting rescuers' advance.

Ekchawin Longpinit from Thai Underground Water Department said the team that dug until 1 a.m. to a depth of 30 meters (98 feet) did not found any wells that would successfully drain water. About a dozen workers were drilling at the same spot Friday morning.

Officials are also trying to find hidden shafts in the mountainside that might offer access.