The funeral of Barbara Bush, the matriarch of a Republican political dynasty, has begun in Texas, with family and friends gathering to pay their respects and celebrate the life of the former first lady.

Bush, only the second woman in US history to have had a husband and son elected President, died Tuesday at the age of 92 at her home in Houston. She had been battling chronic obstructive pulmonary disease and congestive heart failure, and decided against seeking additional medical help earlier this week after a series of hospitalizations.

Her husband of 73 years, former President George H.W. Bush, entered the church with his son, former President George W. Bush, who wheeled him in as members of the family sat down. Former Presidents Barack Obama and Bill Clinton are also in attendance at the funeral.

First lady Melania Trump, along with former first ladies Michelle Obama, Laura Bush and Hillary Clinton, are among the approximately 1,500 expected guests. Many of the women in attendance are wearing strands of pearls, which were a signature accessory of the former first lady.

According to Mrs. Bush’s wishes, the ceremony at the Bushes’ family church, St. Martin’s Episcopal Church in Houston, on Saturday will be a very simple service. Her son, former Florida Gov. Jeb Bush, friend Susan Baker, and presidential historian Jon Meacham will deliver eulogies.

President Donald Trump, who had clashed with the Bush family during the 2016 election, decided not to attend Mrs. Bush’s funeral to “avoid disruptions due to added security” and out of respect for the Bush family. While speaking at a news conference Wednesday, Trump extended his condolences and called Bush a “wonderful, wonderful person” and “a titan in American life.”

On Saturday, Trump tweeted that he was headed to Mar-a-Lago to watch a feed of the funeral, and also tweeted a photo of Bush’s portrait that hangs in the White House.

Trump’s absence from Bush’s funeral is not uncommon for a sitting president. President Obama did not attend Nancy Reagan’s funeral in 2016 or Betty Ford’s funeral in 2011. President George W. Bush did not attend Lady Bird Johnson’s funeral in 2007.

Bush will be laid to rest at the George Bush Presidential Library and Museum in College Station, Texas, buried next to her daughter Robin, who died as a child from leukemia.

Barbara Pierce was born June 8, 1925, in New York. She met George Bush when they were teenagers and they were married in January 1945. As first lady, Bush took up literacy as a cause, raising awareness and eventually launching the nonprofit Barbara Bush Foundation for Family Literacy. Armed with quick wit, Bush was a fierce defender of her family, but she also voiced her personal opinion even if it went against the Republican Party or her husband’s political positions.

When news broke that Bush had passed, tributes to the widely popular former first lady, who was a devoted mother and wife, came pouring in.

“Mom kept us on our toes and kept us laughing until the end. I’m a lucky man that Barbara Bush was my mother,” President George W. Bush wrote of his mother who earned the nickname “the Enforcer” for keeping order at home.

Trump ordered the flags lowered to half-staff this week in memory of Bush. On Friday, more than 6,000 people paid their respects to Bush, who laid in repose at St. Martin’s.

Bush is survived by her husband, George H.W.; sons George W., Neil, Marvin and Jeb; daughter, Dorothy Bush Koch; and 17 grandchildren.

CNN’s John Crawley, Jamie Gangel, Betsy Klein, and Kate Bennett contributed to this report.