Some time this morning, Dominic Mohan, the editor of the Sun, would have received an uncomfortable phone call. Five more of his reporters and executives had been arrested on suspicion of making corrupt payments to public officials – taking the total to 10. One of those held on Saturday is his deputy, Geoff Webster. But he is not the only senior executive who has been held this year: another was former deputy editor Fergus Shanahan.

It is not an exaggeration to say that the sheer number of arrests, and their seniority, means that the paper has been plunged into its most serious crisis since Rupert Murdoch relaunched the title in 1969. Details as to why the journalists have been arrested remain sketchy for the moment but what is clear is that the Operation Elveden investigation into allegations of corrupt payments made by journalists to police officers has been widened to encompass other public officials at the armed forces and presumably elsewhere.

The mood amongst reporters is, in the words of one, "stunned" – which is probably an understatement – coupled with a worry as to where this will end. Could a tip-fee paid five years ago now be considered a bribe? There is no shortage of anger, too. Some of it is directed at the Guardian, stemming from the newspaper's earlier exposé of the News of the World phone-hacking scandal, although much is aimed at the company's Management and Standards Committee that has been providing information to the police which led the Elveden squad to make all its arrests.

It did not take long, either, for speculation to surface from outside Wapping that the Sun could close. At lunchtime, the beleaguered Dominic Mohan issued a rare public statement to shore up the situation, making it clear that he would stay on, "determined to lead the Sun through these difficult times" and that "our focus is on putting out Monday's newspaper".

The message was clear: there would be no resignations, and above all, no immediate closure of the newspaper that is dear to Rupert Murdoch's heart.

However, the police enquiry is far from complete and it is unclear what evidence has prompted the police arrests or even when the alleged offences occurred. Until there is a better picture as to what went on at the Sun it is impossible to form a view as to whether there was a systemic problem to match the industrialised nature of phone hacking as practiced at the News of the World.

For now, the absence of detail also means that the wider public has not formed a view about what has happened at the Sun. Remember, it was a wave of public revulsion that brought the News of the World to the brink last summer.

The scale of uncertainty is such that it is impossible to predict with confidence what will happen next. But if the Elveden investigation is not yet over: one thing is clear – a punch-drunk Sun is owned by an organisation that is at war with itself.