But she said on Friday that the devastating attack that killed an estimated 49 people in Christchurch would not force Muslims to "live in fear."
Omar, who along with Representative Rashida Tlaib is one of the first two Muslim women elected to the House, said that she would attend Friday prayers and called on others to do so as well, Presstv Reported.
"Inna lilahi wa inna ilayhi raji’un. This is chilling news to wake up to. In the face of this horror, I’m mourning with, and holding our community extra close today," Omar wrote.
"We must not live in fear. I will be at Jumu’ah today and I hope others will too. Jummah Mubarak," she added.
The terrorist, a 28-year-old man called Brenton Tarrant, broadcast live footage on Facebook of the deadly attack on one mosque in the South Island city of Christchurch, mirroring the carnage played out in video games. Earlier he published a "manifesto" on Twitter in which he espoused anti-immigrant and Islamophobic ideology, and featured tropes familiar to white supremacist and alt-right movements.
Tarrant also expressed support for US President Donald Trump as a “symbol of renewed white identity and common purpose.”
The vile terrorist said he was inspired by Anders Breivik -- the Norwegian far-right mass murder who committed the 2011 Norway attacks where he killed 77 people -- and called for the deaths of German Chancellor Angela Merkel, Turkish leader Recep Erdogan and London Mayor Sadiq Khan in his "manifesto".