Vice President Mike Pence and second lady Karen Pence will travel to Texas on Wednesday to speak with victims of the mass shooting at First Baptist Church in Sutherland Springs.

"Karen and I will travel to Sutherland Springs on Wednesday to meet with families of the fallen, injured and law enforcement. We are with you Texas," Pence tweeted on Monday afternoon.

Twenty-six parishioners, ranging in age from 18 months to 77, were killed during a worship service when a gunman opened fire inside the small church near San Antonio on Sunday. The alleged shooter, 26-year-old Devin Patrick Kelley, was wearing a bulletproof vest and black clothing when he entered the church and used an AR-556 to carry out the attack.

Federal investigators said Kelley's mother-in-law, with whom he had a strained relationship, regularly attended the church but was not present on Sunday. Dozens of other people were injured during the mass shooting — the largest in Texas state history — and 10 remain in critical condition.

"We know that his ex- in-laws or in-laws came to church here from time to time. They were not here yesterday, so we don't know why he actually showed up yesterday," Wilson County Sheriff Joe Tackitt told CNN on Monday.

Both Pence and President Trump, who is currently overseas for a five-country tour through Asia, issued statements after the massacre and ordered all flags to be flown at half-staff through Thursday to honor the victims and their families.

Kelley is said to have purchased four guns over the past four years from various sellers in Texas and Colorado. The former U.S. Air Force member was discharged for bad conduct in 2012 and had spent a year in prison for assaulting his wife and young child.

Johnnie Langendorff, a Texas native who happened to be passing by First Baptist Church during the shooting Sunday morning, noticed something was off when he saw Kelley exchanging gunfire with another man in the church parking lot. Langendorff and the man Kelley was shooting at teamed up and chased the shooter down the freeway at 95 mph until Kelley crashed his vehicle into a ditch nearly 11 miles away from the church.

Authorities are still working to determine whether Kelley, who was found dead with gunshot wounds, was fatally shot by the man riding passenger in Langendorff's car or turned his gun on himself after crashing.