Twenty people have been killed and 26 others wounded after a man armed with a rifle opened fire at a shopping mall in the US border town of El Paso, Texas, on Saturday. Many shoppers in the busy Walmart store were buying back-to-school supplies when they found themselves caught up in the latest US mass shooting, which came just six days after <a href="https://www.thenational.ae/world/the-americas/three-dead-as-gunman-opens-fire-at-california-food-festival-1.891977">a teenage gunman killed three people at a summer food festival in Northern California.</a> Saturday's suspect was officially identified as a white male 21, from Allen, Texas, a Dallas suburb about 1,046km east of El Paso, which lies along the Rio Grande, across the US-Mexico border from Ciudad Juarez. Citing law enforcement officials, several media reports named the suspect as Patrick Crusius. El Paso police chief Greg Allen said authorities were examining a manifesto from the suspect indicating "there is a potential nexus to a hate crime". Officials declined to elaborate and said the investigation was continuing. But a four-page statement posted on 8chan, an online message board often used by extremists, and believed to have been authored by the suspect, called the Walmart attack "a response to the Hispanic invasion of Texas". It also expressed support for the gunman who killed 51 people at two mosques in Christchurch, New Zealand. CNN reported that the FBI has opened a domestic terror investigation into the shooting. The carnage ranked as the eighth-deadliest mass shooting in modern US history, after a 1984 shooting in San Ysidro, California, that claimed 21 lives. Those injured in the shooting were taken to two separate hospitals, medical officials said. At least eleven victims were received at the Del Sol Medical Centre, a spokesman said. Others were taken to the University Medical Centre of El Paso. City police issued a call for blood donations in a tweet. "Blood needed urgently. Multiple injured transported to various hospitals," the El Paso Police Department posted. Law enforcement first received calls relating to an active shooter at the Cielo Vista Mall at about 10am local time. In the chaos of the shooting, there were also reports of a separate shooting several miles away but the scene at that mall was later deemed to be safe. The FBI, the local sheriff’s department and other agencies were in attendance at the shopping mall to assist the authorities in El Paso. The Associated Press reported US President Donald Trump was being updated on the situation as it unfolded. Mr Trump had also reportedly spoken with both Attorney General William Barr and Texas Governor Greg Abbot. In a tweet the US president said many had been killed in the shootings. “Terrible shootings in El Paso, Texas. Reports are very bad, many killed. Working with State and Local authorities, and Law Enforcement. Spoke to Governor to pledge total support of Federal Government. God be with you all!” he wrote. Mr Abbott called the shooting "a heinous and senseless act of violence," as he said he would travel to El Paso, which has about 680,000 residents and sits across the border from Juarez, Mexico. At a Democratic presidential candidate forum in Las Vegas, former Texas congressman Beto O’Rourke, from El Paso, broke the news of the shooting to his audience and announced he would be returning home. "El Paso is the strongest place in the world. This community is going to come together. I'm going back there right now to be with my family, to be with my home town," the Democratic presidential hopeful said. Later, speaking to reporters outside a hospital in El Paso where he was visiting victims of the shooting, Mr O'Rourke accused Mr Trump of inciting hatred. He said Mr Trump had proven himself a racist with his recent attacks on four ethnic minority congresswomen and his past branding of Mexicans as rapists. "He is a racist and he stokes racism in this country. And it does not just offend our sensibilities, it fundamentally changes the character of this country and it leads to violence," Mr O'Rourke said. "We've had a rise in hate crimes every single one of the last three years during an administration where you have a president who's called Mexicans rapists and criminals." Mr O'Rourke was responding to questions about the manifesto purportedly written by the gunman. More than 80 per cent of El Paso's population is Hispanic, according to US census figures. Asked if any of the contents of the manifesto should "fall at the feet" of Mr Trump, Mr O'Rourke replied: "Yes." "There are still details that we are waiting on but I'm just following the lead that I've heard from the El Paso police department where they say there are strong indications that this shooter wrote that manifesto and that this was inspired by his hatred of people here in this community."