More than half a million pounds has been raised for the families of two police officers killed when joyriders crashed into them on a dual carriageway.PC Matthew Blades, 37, and PC Tom Clough, 38, died early on Saturday when a Volkswagen Passat travelling the wrong way down the A66 near Middlesbrough crashed head-on into their police car.Five young men travelling in a car in the wrong direction were also killed. Twelve people have been arrested in connection with the tragedy.Two GoFundMe pages have been created for the officers' families, with Cleveland Police Federation's fundraiser collecting more than £519,000 from 19,500 donors as of 4pm today.The federation said its officers had 'paid the ultimate sacrifice in the line of duty' and left behind 'heartbroken loved ones'.It added the funds raised would be split equally between the families.A second fundraiser, launched by former Cleveland Police officer Paul Cooper, raised a further £37,000 for the officers' relatives from 1,700 people.Lauren Somerville, the federation's boss, said she was 'simply staggered' at the scale of donations made in less than a day.Thanking donors, Ms Somerville said the 'small force' felt the death of their colleagues 'deeply' and had been left 'completely numb'. PC Matthew Blades, a father-of-two, was killed after his police car was hit head-on by a Volkswagen Passat driving the wrong way down the A66 near Middlesbrough PC Tom Clough also died in the crash, which happened ten seconds after a police pursuit of the Volkswagen was called offA fundraiser for the officers' families passed £480,000 on Monday afternoon, while a second page raised a further £36,000