At least two people have been killed and 300 injured as Venezuelan security forces fired tear gas on protesters trying to deliver humanitarian aid from neighbouring countries.The day of violence saw police and activists square off on two bridges connecting Venezuela with Colombia.Juan Guaido, the man the US recognises as Venezuela's interim president, made repeated calls for the military to join him in the fight against Nicolas Maduro's "dictatorship".Image:Smoke billowed from the trucks set alight on the Francisco de Paula Santander bridgeAn estimated 60 soldiers heeded his call, although most were lower in rank and did not seem to dent the higher command's continued loyalty to Mr Maduro's socialist government.Almost 200 tonnes of aid in a convoy of trucks has been waiting to cross several border bridges - including food and medicine - and the tear gas was fired as protesters tried to stop the aid from being destroyed.Mr Guaido said he will meet with the Lima Group of nations - 14 countries seeking an end to the crisis in Venezuela - in Bogota on Monday with US Vice President Mike Pence.Image:People rushed to get the aid off the burning trucksThe interim president is hoping diplomacy could lead to a breakthrough in the crisis and apply further pressure on Mr Maduro.As night fell, Mr Guaido made an impassioned plea to troops.

As he stood alongside a warehouse where 600 tonnes of supplies have been stockpiled, he said: "How many of you national guardsmen have a sick mother How many have kids in school without food"You don't owe any obedience to a sadist who celebrates the denial of humanitarian aid the country needs."'We've got to do it today' - Sky's Cordelia Lynch meets protesters in CucutaOne man, who was left with a bloody wound after being struck on the forehead with a tear gas canister during Saturday's unrest, said: "They burned the aid and fired on their own people.

That's the definition of dictatorship."Protesters formed a human chain to pass back as much salvaged aid as they could as smoke billowed from barricades built to stop the supplies getting in.

Other demonstrators threw rocks at heavily armed police.Image:A demonstrator kicks a burning tyre in UrenaVenezuelan officials have closed the border with Colombia, Brazil and the island of Curacao and have been cracking down on those trying to keep them open.Mr Maduro said he had cut all diplomatic relations with Colombia's "fascist government" and was expelling its diplomats in response to its support for Mr Guaido.Image:A man faces off against Venezuelan police at the Simon Bolivar bridge in CucutaSpeaking to supporters in Caracas, the Venezuelan capital, the embattled president said: "Patience is exhausted, I can't bare it anymore, we can't keep putting up with Colombian territory being used for attacks against Venezuela."Opponents claim Mr Maduro presided over a fraudulent election and has let the economy go to ruins with rampant inflation and people struggling to get food and medicine.Image:The trucks were said to have been set alight by National GuardsmenMost of the aid at the Colombia border has been provided by the US, which has recognised Mr Guaido as the interim president despite Mr Maduro refusing to stand down.Venezuelan authorities regard the plan to bring in aid as a veiled US-backed invasion.Image:Venezuelan national guards clash with demonstrators in UrenaTensions first flared at dawn, when residents in Urena began removing yellow metal barricades and barbed wire blocking the Francisco de Paula Santander bridge.At another border crossing, the Simon Bolivar bridge, about 10 miles (15km) south, Colombian migration authorities said four National Guardsmen had deserted their posts and asked for help.Image:A protester kicks over one of the barricadesPictures showed young men struggling to get through a crowd, holding their assault rifles and pistols above their heads in a sign of surrender.They were then ordered to lay on the ground as migration officials held back onlookers.Juan Guaido, the head of Venezuela's National Assembly, declared himself interim president under the constitution on 23 January.He has been backed by dozens of countries, including the UK.Image:A woman throws an object at police in UrenaOn Friday, he attended a concert staged by Sir Richard Branson, in Cucuta, on the Colombian side of the border, opposite Urena.Mr Guaido met Colombian president Ivan Duque at the Live Aid-style event, despite Mr Maduro forbidding him from leaving the country.Image:A protester is hit in the face by barbed wire during battles with guards in UrenaSky's Cordelia Lynch, who is in Venezuela, said hundreds of people at the concert were planning to join the battle to get the trucks across the border.She said Mr Guaido had been talking to the authorities to get permission to bring across 14 trucks, each laden with about 20 tonnes of aid in a shipping container.Image:The moment two Venezuelan guards hand themselves to the Colombian authoritiesProtests also took place on Saturday in Curacao and in the capital Caracas - where a protest was held by Mr Maduro's supporters.He told the crowds he was ready to defend Venezuela's independence with his life if necessary.