A shop worker who dialled 999 as a colleague screamed for help on Monday night has spoken about the dramatic events that unfolded on Letchworth’s Grange estate.

Tesco Express customer assistant Mukinthan Singham, who was working in the store with his two colleagues, told the Comet: “When I heard my colleague screaming, I ran over to see what had happened.

“Then I saw a man with a black baseball bat in his left hand grabbing her neck with his free hand while wearing cream-coloured women’s tights on his head as a mask.

“He was shouting ‘open the till’ repeatedly.”

The 38-year-old – who lives in Stotfold – said his colleague was frightened and screaming, but the masked man was pushing her towards to till.

He said: “I went towards the till, but the man grabbed the money and made his way out of the store with his baseball bat swinging. There were no customers in the store.

“I called 999 and started chasing him.”

The robber is believed to have taken hundreds of pounds in cash.

Investigating officer Det Con Ben Dixon said: “We are still investigating to establish the full circumstances of what happened that night and I would like to hear from anyone who was in the area of the shop and the park and witnessed what happened to contact me.

“The money taken from Tesco Express has not yet been recovered and I would also appeal to anyone who knows where this may be to contact me.”

Anyone who can assist is asked to contact the non-emergency number 101 or Crimestoppers anonymously on 0800 555 111.

Two teenagers have been arrested in connection with a fight which broke out after the robbery.

Officers called to the Middlefields store at about 9.10pm on Monday night following the original attack report that there was also an altercation between a man and four other men, in which money was allegedly stolen.

An 18-year-old man and a 19-year-old man were arrested yesterday on suspicion of robbery in connection with the altercation. The two teenagers – who are both from Letchworth – have been released on police bail until Thursday, December 3.

A 55-year-old man from Letchworth has also been arrested in connection with the robbery. He has been released on police bail until Wednesday, December 2.