Tennessee elected officials have asked US President Donald Trump for federal assistance in the wake of Friday's downtown bombing, but five days later the White House has yet to issue an emergency declaration.

Now nobody can get dragooned into supporting yet another war on a Muslim-majority country, says a political commentator.

US police officers on Sunday provided harrowing details of responding to a Christmas morning explosion in downtown Nashville, at times getting choked up reliving the moments that led up to the blast and offering gratitude that they were still alive.

The 63-year-old suspect in the bombing that rocked Nashville on Christmas morning is killed in the blast that destroyed his motor home and damaged more than 40 businesses, authorities said on Sunday.

Tennessee governor asks Trump for emergency aid after the Christmas Day bomb blast in Nashville.