Egypt sailors missing after navy ship attacked in Med
Gunmen have attacked an Egyptian navy ship in the Mediterranean Sea, state media say, leaving five servicemen injured and eight more missing at sea.
The vessel reportedly caught fire in the assault, some 70km (45 miles) off the northern port of Damietta.
In two further attacks in northern Sinai, militants killed five policemen and soldiers, officials said.
A three-month state of emergency was declared in northern Sinai last month after 31 soldiers were killed.
Jihadists have stepped up attacks against police and soldiers since the overthrow of Islamist President Mohammed Morsi last year.
However, direct attacks on Egyptian naval vessels are unusual.
The group behind the latest attack, which happened on Wednesday, has not yet been identified.
'Air force deployed'
Four fishing boats were used in the assault by "terrorists", four of whom were killed, the military said.
Another 32 were arrested and were being interrogated, it added.
Analysis: Orla Guerin, BBC News, Cairo
If this was a militant attack in the Mediterranean, as the Egyptian army has said, then it's the opening of a new front.
The military says "terrorist elements" struck at dawn on Wednesday. More than a day later it has not released any information about the alleged assailants.
The incident happened north of the port of Damietta, where armed people traffickers are known to operate. Did they clash with the navy to protect their lucrative trade?
Or was the vessel targeted because it was carrying troops to the Sinai peninsula, as some are suggesting on social media ? A former general says that's unlikely as the ship was too far out to sea. But there is speculation that militants targeted the vessel in revenge for the military's growing crackdown in Sinai.
Many questions remain about the waterborne assault. One retired brigadier has described it as "bewildering."
Local media reported that the Egyptian air force had been deployed to deal with the attackers.
The Egyptian navy frequently intercepts migrant smugglers and drug traffickers off its Mediterranean coast.
In one of the Sinai attacks, two policemen who were not in uniform were shot dead near Rafah by gunmen.
In a separate attack on Thursday, three Egyptian soldiers were also shot dead after their car was stopped near Sheikh Zuweid, several miles to the west of Rafah.
A small bomb also exploded in a train carriage on Cairo's underground system, which led to 16 people being injured in the panic that followed. The blast occurred at the Hilmiyat al-Zaytun station in eastern Cairo on Thursday.
The latest attacks come several days after Egyptian jihadist group Ansar Beit al-Maqdis pledged allegiance to Islamic State (IS) militants, who have taken control of swathes of Syria and Iraq.
Ansar Beit al-Maqdis - or Champions of Jerusalem - has been behind a string of attacks on military and police targets in its stronghold in Sinai.
A three-month state of emergency was declared there last month after 31 soldiers were killed in two separate militant attacks near El-Arish on 24 October.
In a separate development on Wednesday, Egypt's President Abdul Fattah al-Sisi signed a new law allowing for the extradition of foreign nationals sentenced or charged in Egypt.
It is believed the law may pave the way for the release of three non-Egyptian Al-Jazeera journalists, including Australian Peter Greste, who have been held for almost a year.