Washington, DC [US] September 12 (ANI): US President Donald Trump on Thursday (US local time) said investigators are making progress in tracking down the suspect behind the assassination of conservative activist Charlie Kirk, calling the killer 'a total animal.'

Trump told reporters he had spoken at length with Kirk's widow, Erika. 'We had a long talk, and she's devastated. She's absolutely devastated, as you can imagine,' he said.

When asked about a possible motive for the attack, Trump said he had 'an indication' but declined to share details. 'We'll let you know about that later,' he added.

Kirk, 31, was shot in the neck on Wednesday while answering a question on mass shootings during an open debate at Utah Valley University, as per The New York Times. He is survived by his wife, Erica, and two young daughters.

A prominent conservative activist, Kirk was the founder of Turning Point USA and often travelled to college campuses promoting free speech.

Trump was also asked about his own safety in the wake of the killing. 'Not really,' he replied, though he confirmed that his security measures had been increased. He said his real concern was the safety of the country, blaming what he called the 'radical left' for fostering political violence.

'We have a great country. We have a radical left group of lunatics out there, just absolute lunatics, and we're going to get that problem solved. I'm only concerned for the country,' Trump said.

On Wednesday night, Trump had earlier described the killing as a 'dark moment for America.' In an emotional statement, he said Kirk was a patriot who 'devoted his life to open debate and to the country he loved so much.'

'He's a martyr for truth and freedom,' Trump said, while accusing political opponents of spreading a culture of hatred against conservatives.

As a mark of respect, Trump ordered American flags to be flown at half-mast until September 14 across federal buildings, military posts, naval stations, and US embassies worldwide. (ANI)