A pastor has shot dead a retired minister in a retirement home.

Allen Smith, an 80-year-old retired Baptist minister, was shot twice in the head by Ted Merchant, 67, during their regular late night Bible study at Senior Suites of Rainbow Beach in Chicago.

Smith died on the scene. Merchant fled but was later apprehended by Police. The incident was caught on CCTV and he now faces charges of first degree murder.

Merchant was a fellow resident, active in leading a ministry there. He and Smith were known for their discussions and "little arguments" over the Bible, the Chicago Tribune reports.

Residents expressed their shock at what had occured.

"They'd be out there [on the patio] all the time," said Dorothy Hull. "They'd talk about Bible passages and ideas about God. They always had little arguments going on about things like that.

"It was very surprising," she added. "I just can't get over it because he [Merchant] had a church in the community room every Sunday morning. He was retired too, but he had this church going on. I just couldn't believe he did that."

Merchant was reportedly "trying to get his ministry off the ground". He called himself a pastor, and held prayer gatherings. Ann Harding, another resident, said: "He was a nice man, you know, when he came to the door."