The state Department of Land and Natural Resources closed a popular hiking trail near downtown Honolulu on Monday after a massive banyan tree fell on a woman and seriously injured her.

The woman, in her early 40s, was hiking with a group of eight, including multiple children, when the tree came crashing down near the start of Judd Trail in the Nuuanu area, said Honolulu Fire Department Capt. David Jenkins.

The hikers had just crossed the stream and were about five minutes into the hike when the tree fell, Jenkins said.

He described the tree as “big — really, really big,” about 70 feet tall with a canopy about 70 feet wide.

Firefighters responding to the scene at about 11:20 a.m. found the woman pinned by the tree. Other members of the hiking party escaped without injury or with minor scrapes.

Firefighters placed the injured hiker in a rescue basket and lifted her by helicopter to an area off Old Pali Road where paramedics were waiting.

An Emergency Medical Services report said paramedics treated the woman for multiple injuries and transported her in serious condition to a hospital.

It was unclear Monday what caused the tree to fall. DLNR spokeswoman Deborah Ward said a sign was posted closing the trail for safety reasons after the tree fell across the trail and Nuuanu Stream.

An arborist will assess the fallen tree today and try to determine what caused it to fall and whether it will be safe for state crews to move it. The trail will remain closed until the tree can be removed.