Both sides of the "Brexit" referendum have suspended their campaigns for a second day after a member of parliament was attacked and killed yesterday.

The vote on whether the U.K. should stay in the European Union is due to take place next week. The campaign had reached fever pitch prior to the attack. A poll by Ipsos Mori for the Evening Standard newspaper had put "leave" six percentage points ahead of remain.

There was also strong central bank intervention with the Federal Reserve, Bank of Japan, Bank of England and Swiss National Bank warning on the impact of a possible exit.

Jo Cox, the Labour MP for Birstall in northern England, was shot and stabbed several times in her constituency town of Birstall around 1 p.m. on Thursday. She later died.

Cox had been campaigning to stay in the E.U. Her husband and two children took part in a pro-E.U. flotilla on the River Thames on Wednesday.

A 52-year-old man has been arrested in connection with the murder. Police are investigating the motive for the murder. Local media has reported that the suspect shouted "Britain first" or "put Britain first" during the attack.

Britain First is a far-right political party in the U.K. that is campaigning for a "Brexit." The party, however, has suggested the reports were "hearsay"  and condemned the attack on Cox.

Britain is in shock over the murder as shootings are very uncommon in the U.K. Flags are flying at half-mast over parliament and Buckingham Palace.

Prime Minister David Cameron has cancelled his appearances and said, "It's right that we are suspending campaigning activity in this referendum and everyone's thoughts will be with Jo's family and her constituents at this terrible time."

The pound, which had fallen sharply in recent weeks, rebounded. It was recently trading at $1.4240, up 1.5% from last week's low.

Betting odds swung more in favor of a "remain" vote after the attack, Mizuho Bank noted. 

The FTSE 100 was 1.14% up in early trading at 6,019.17.