BOULDER, Colo. -- A combined funeral service will be held in Lafayette Saturday for brothers Mark and Bob Matthews, who lost their lives in a mid-air collision over Boulder last week.

"The two men had a huge impact on their families and communities and touched hundreds, if not thousands, of lives," the brothers' families said in a statement Tuesday. "The family would like to spread the word about the funeral so those who knew these wonderful men can say goodbye.

"Thanks for all of your support and kindness during this tough time," the statement said.

Mark Matthews, 56, and his 58-year-old brother, Bob Matthews, were both on a Cirrus plane that collided with a Piper Pawnee Saturday afternoon.

The Piper pilot, Alexander Howard Gilmer, 25, of Evergreen, also died.

The brothers' funeral will be held Saturday at 11 a.m. at the Immaculate Conception Catholic Church, 715 Cabrini Drive, in Lafayette.

Neighbors told TheDenverChannel.com that the brothers were very involved in their community.

Bob Matthews was a water rights lawyer, in Boulder. Mark Matthews owned an engineering company, in Englewood.

The families ask that donations be made in the Matthews brothers' names to the Sister Carmen Center at 701 W. Baseline Road, Lafayette, CO 80026. Bob Matthews served on the board of the nonprofit agency, which provides food, clothing and other emergency services to needy community members.

Longtime friend and neighbor John Annear described Mark Matthews as "just a great guy. Just a family man, always there for you."

Annear said the plane belonged to Bob Matthews.

"He was a very conscientious pilot. No safer pilot that I’m aware of," said Annear.

He said the two brothers were very close and enjoyed spending time together.

"And that was Saturday. It was just a pleasure ride around the Boulder area," Annear said.

Federal accident investigators are probing the cause of the collision.