Heavy rain Wednesday night raised stream levels in Maunawili, trapping 16 hikers and causing a small rockslide that closed a lane on Pali Highway in Kailua.

The rain prompted a flood advisory for Oahu, in effect until 12:30 a.m. today, for areas including Honolulu, Maunawili, Kahaluu, Waimanalo, Waikane, Waiahole, Kaneohe and Waimanalo Beach.

Flooding forced the second closure of a Kailua- bound lane on Pali Highway Wednesday night just after the tunnel.

Police reported the closure about 9:15 p.m. and said the lane was closed to the first runaway truck ramp.

At about 7 p.m., a small rockslide closed one Kailua- bound lane just after the tunnel, but firefighters quickly cleared the rubble, which consisted of about a half-dozen boulders, said Honolulu Fire Department Capt. David Jenkins. The lane was reopened about 30 minutes later.

Rising streams from heavy rainfall also trapped 16 people on Maunawili Trail at about 6 p.m. Wednesday.

Two adults and three children called for help at about 5:30 p.m. when the weather worsened and the streams began to rise, Jenkins said.

They were able to make it back to the trailhead, but soon after a second party of four called firefighters for help because they were trapped by rising streams. Firefighters hiked to the party and escorted them out.

At about the same time, a third party that was highest on the trail called for help because they were trapped by flooding. A fire helicopter reached the group of seven where they were stranded above the waterfall and transported them to a safer area where firefighters hiked to them and escorted them out of the trail, Jenkins said.

None of the 16 people were hurt. Jenkins said firefighters helped the last hikers out by 7:30 p.m.

Forecasters say more rain, thunderstorms and even snow on Mauna Kea and Mauna Loa are possible tonight as unstable and moist air moves over the state.