A man arrested in the seemingly random shooting of a woman at a San Francisco pier has admitted in a jailhouse interview that he shot her, but says it was an accident.

Francisco Sanchez told KGO-TV on Sunday that he was responsible for 32-year-old Kathryn Steinle's death, but insisted that the shooting was accidental.

Speaking in a mix of Spanish and English, he said he found a gun wrapped inside a shirt and when he picked it up, he heard three shots go off.

Steinle was gunned down while out for an evening stroll along the waterfront with her father and a family friend on Wednesday.

Police said witnesses heard no argument or dispute before the shooting, suggesting it was a random attack.