A 17-year-old girl has been charged with murder by aiding and abetting after prosecutors say she recorded a livestream of an attack on a San Diego mosque that left three people dead.

Prosecutors say the girl also published a manifesto from two teenage gunmen who carried out the attack on the Islamic Center of San Diego on 18 May.

The teenager, from North Carolina, was arrested last week and indicted by a grand jury on Monday, according to Forsyth County District Attorney Jim O'Neill.

Speaking at a news conference, O'Neill said: "The thought of her going back to school, with the weekend approaching, holy days approaching, we didn't know what she was capable of."

The teenager now faces three murder charges and one count of conspiracy. O'Neill explained that under North Carolina law, a person accused of aiding and abetting a crime can be held criminally responsible in the same way as the person who carried it out.

Authorities say the attack was carried out by two males - aged 17 and 18 - who opened fire at the mosque, before taking their own lives.

O'Neill said the pair had two aims that day: "Number one, to kill as many people as possible on that day. Secondly, they wanted this carnage and destruction recorded ... livestreamed."

A security guard at the mosque, Amin Abdullah, exchanged gunfire with the attackers and initiated a lockdown, helping protect around 140 children who were inside the building.

Abdullah and two worshippers - Mansour Kaziha and Nader Awad, who drew the attentions of the shooters in a parking lot - were fatally shot.

San Diego Police Chief Scott Wahl previously described Abdullah's actions as "heroic", saying they had "undoubtedly" saved lives.

According to investigators, the shooters recorded the attack using cameras mounted on GoPro-style helmets. O'Neill said the pair had also planned further attacks "at a local Jewish temple and finally at a predominantly African American high school".

Authorities said the teenagers had an arsenal of around 30 guns and a crossbow, which investigators say were taken from one of the shooter's parents.

The document, which was reviewed by the BBC's US news partner CBS News, pointed to a gunman who murdered 51 people at two mosques in Christchurch, New Zealand, in 2019, as one of their models.