Five children orphaned after parents killed on mum's birthday trip

Five children have been left orphans after their parents were tragically killed on a family holiday in the US.

Jessica and Jake Woodruff, 36, were killed instantly when a redwood tree fell on their 2016 Honda as they drove along Route 199 highway in Del Norte County in California last week.

The family, from Yreka, had been on their annual trip up the coast for Jessica's birthday. She was 45.

A crowdfunding campaign has raised more than $350,000 for the couple's children in just four days.

"This was a shocking and unexpected event, and the tragedy of this accident makes it difficult to accept as real," Amanda Maffei, the organiser of fundraiser said in a post.

"It will be with every ounce of power for the three little ones to stay together and continue to be raised by their elder (and amazingly strong and selfless) siblings, Megan and Evan."

Maffei said the amount of support, both financial and emotional, the family have received since the tragedy has been overwhelming.

"The amount you all have done for these children and their future already is absolutely humbling," she wrote.

"There is no getting around the devastation and trauma the loss of Jessica and Jake has brought, and as we can all imagine, there is a long road ahead, especially for the children who have been left behind."