"The club, (with) 300 or 400 people… coming — they should have good security. If there was good security, he wouldn't have had this opportunity. Why the law enforcement team was so late — they should have neutralized him quick… This should not have happened," Seddique told Sky News.
He added his son's actions were not influenced by religious views, saying that only Omar himself was responsible for what he had done.
"I don't forgive what he did — it's unforgivable because we didn't teach him to do this. I taught him to become more educated and more service-oriented towards the community," Omar's father continued.
On Sunday, Mateen, identified as a US citizen of Afghan descent, killed 49 people and injured 53 others at Pulse nightclub in Orlando. Mateen was reported to have been trained in the use of weapons. According to media reports, in 2013, he was investigated by US law enforcement for possible ties to terrorist organizations and a Florida man, who became the first US suicide bomber in Syria.