New Zealand Prime Minister Jacinda Ardern has vowed to reform her country's gun laws in response to the worst mass shooting in the country's modern history. Fifty people were killed when a gunman opened fire Friday at two different mosques in Christchurch. The 28-year-old suspect allegedly targeted Muslims because of his white nationalist and anti-immigrant views.

Thirty-one people remained hospitalized on Monday, including nine in critical condition.

"To make our communities safer, the time to act is now," Ardern said, adding that the government had agreed on new gun laws to be implemented within the next 10 days -- swift action in response to the mass shooting, but with very few details, reported CBS News correspondent Ben Tracy.

"When Australia found itself tragically in a similar position to what we find ourselves now, they took 12 days to make their decision. We have taken 72 hours," Ardern said.

She was alluding to Australia's reaction in 1996 after a mass shooting there left 35 people dead. A government-funded gun buyback and a virtual ban on owning semi-automatic rifles cut private gun ownership by almost a third. Australia now has one of the lowest gun murder rates in the world.

The FBI is assisting what New Zealand police have called their largest-ever criminal investigation.

All five guns used in Friday's rampage were purchased legally in New Zealand, including two semi-automatic rifles. A gun shop owner said the attacker purchased four guns from him through a "police-verified online mail order process," but it was unclear whether any of those firearms were used in the shootings.

The alleged shooter was formally charged with murder over the weekend. By law, his face was blurred in images broadcast of him standing in the courtroom. Authorities said the Australian native acted alone and was not on any terrorist watch lists.

On Monday, police searched two homes in Australia near where he once lived.

Mazharuddin Syed Ahmed was inside the Linwood mosque during the shooting on Friday. He lost seven of his close friends.

"I can't put it to words," Ahmed told CBS News. "It's a very closely knitted community so, yeah, it's like we lost all the good people there."

The two mosques where the shootings took place were still closed on Monday, but police hoped to have them open by the end of the week.

Meanwhile, the alleged shooter has apparently fired his lawyer and plans to represent himself. The fear is that he will use his trial as a platform for his white nationalist beliefs.

The world was also learning more on Monday about some of the people killed in the attack. The youngest was just three years old.

A makeshift memorial has become a focal point for the Christchurch community, which remained in shock three days after the attack. Tracy said he saw many people stand there with tears in their eyes, wondering how something like this could happen in New Zealand, one of the safest countries in the world.