HOUSTON, United States (AP) — Former ambassadors along with sports and entertainment stars arrived on a gray, cloudy day to attend Saturday’s private funeral for Barbara Bush at the nation’s largest Episcopal church — a day after more than 6,000 people paid their respects to the woman known by many as “America’s matriarch.”

Flags were flown at half-mast for the wife of the nation’s 41st president and mother of the nation’s 43rd. The first attendees arrived on city buses escorted by Houston police motorcycle units Saturday morning, and walked into St Martin’s Episcopal Church in Houston in a light drizzle of rain.

They included former Rep. Gabby Giffords and her husband, retired astronaut Mark Kelly, and professional golfer Phil Mickelson, along with Karl Rove, and other former White House staff.

About 1,500 people are expected at Saturday’s private service, including four former presidents: Bush’s husband, George HW Bush, and their son, George W Bush, along with Bill Clinton and Barack Obama.

First lady Melania Trump will be at the service, but the White House said this week that President Donald Trump wouldn’t attend “to avoid disruptions due to added security, and out of respect for the Bush family and friends attending the service.”

The cavernous sanctuary of the church was adorned with sprays of yellow garden roses, yellow snap dragons, antique hydrangeas and other flowers.

Burial will follow at the Bush Library at Texas A&M University, about 100 miles (161 kilometers) northwest of Houston. The burial site is in a gated plot surrounded by trees and near a creek where the couple’s 3-year-old daughter, Robin, who died of leukemia in 1953, is buried.

In a statement released Friday, the family said Barbara Bush had selected son Jeb Bush, the former Florida governor, to deliver a eulogy along with her longtime friend Susan Baker, wife of former Secretary of State James A. Baker III, and historian Jon Meacham, who wrote a 2015 biography of her husband.

The funeral program shows that her grandchildren will also play prominent roles: her granddaughters will offer a reading during the service and her grandsons will serve pallbearers.

On Friday, a total of 6,231 people stopped by the church to pay their respects. Many of the women wore the former first lady’s favorite color, blue, and trademark pearls.

After seeing how many people had lined up to pay their respects to his wife, former President George H.W. Bush decided to attend — he sat at the front of the church in a wheelchair, offering his hand and smiled as people shook it, for about 15 minutes.

Barbara and George Bush were married longer than any other presidential couple when she died Tuesday at their home in Houston. She was 92.

One of just two first ladies to have a child elected president, Barbara Bush was widely admired for her plainspoken style and her advocacy for causes including literacy and AIDS awareness.

Barbara Bush was known as the “Enforcer” in her family, the glue who kept the high-powered clan together. Eight of her grandsons will serve as pallbearers.